Fig 2: High GPRC5A is associated with poor survival and chemotherapy resistance in HGSC patients AFlow diagram of patients for the HGSC TMA.BRepresentative immunostainings for GPRC5A scoring in HGSC primary and metastatic tumors. For maximum intensity scores, an optical 4‐point scale (0: negative, 1: mild, 2: moderate, and 3: high) was used. For survival analyses, a 2‐point scale (low: scores 0–2 and high: score 3) was used. Scale bars: 200 μm.C, DKaplan–Meier survival curves illustrate the overall (OS) and progression‐free (PFS) survival of patients with high or low GPRC5A. In primary tumors, mean OS for GPRC5Ahigh was 39 months vs. 56 months for GPRC5Alow (C). In patients with metastatic tumors, mean OS for GPRC5Ahigh was 37 months vs. 60 months for GPRC5Alow. Mean PFS in metastatic tumors was 20 months for GPRC5Ahigh vs. 35 months for GPRC5Alow (D). No significant difference in mean PFS in primary tumors.ECorrelation of maximum GPRC5A intensity with objective response rate (ORR) and treatment sensitivity (platinum alone or in combination with taxane).F–IKaplan–Meier survival estimates for the PFS of patients with high or low (top 25% vs. bottom 25%) GPRC5A (F), EPHA2 (G), GPRC5A + EPHA2 (H), and GPRC5A + EPHA2 + RSK1(RPS6KA1) + RSK2(RPS6KA3)‐combined (I) mRNA expression. Mean PFS for GPRC5A + EPHA2high was 15 months vs. 26 months for GPRC5A + EPHA2low (H). Mean PFS for GPRC5A + EPHA2 + RPS6KA1/3high was 14 months vs. 31 months for GPRC5A + EPHA2 + RPS6KA1/3low (I).Data information: In (C, D and F–I), logrank test was used. In (E), Pearson chi‐square test was used.

Fig 3: Oncogenic EphA2 signaling switch is associated with platinum resistance and mediated by treatment‐activated ERK1/2‐RSK axis in OC cells A, BImmunoblot images show EphA2 (A; total, pS897, and pY588) and corresponding pS897/pY588 ratios (B) of TYK‐nu and TYK‐nu.R after treatment with 0–10 μM cisplatin for 72 h. N = 5.C, DEphA2 (total and phosphorylated) in the cells treated (C) and untreated (D) with 0–80 μM carboplatin for 72 h.E, FEphA2 (total and pS897) in TYK‐nu after treatment with inhibitors against MEK (UO126, 10 μM), PKA (H89.2HCl, 10 μM), PI3K (LY294002, 10 μM) or its alpha subunit (BYL‐719, 5 μM), and RSK (BI‐D1870, 10 μM) in combination with 0–10 μM cisplatin for 72 h (E). Corresponding EphA2‐pS897 quantification for BI‐D1870 treatment (F). N = 5.GEphA2 (total and pS897) in TYK‐nu.R treated with 0–20 μM cisplatin without or with 10 μM BI‐D1870 for 72 h.H, IEphA2, RSK, and ERK1/2 (total and phosphorylated) in TYK‐nu (H) and OVCAR4 (I) treated with 0–30 μM carboplatin without or with 50 μM LJH685 for 72 h.Data information: In (B and F), data are presented as mean (SD). *P < 0.05, **P < 0.01. Exact P‐values are provided in Appendix Table S10, Student's t‐test.Source data are available online for this figure.

Fig 4: Effect of MSP on RON phosphorylation and activation of downstream signal molecules. 5637 cells (2 × 106 cells per 60-mm culture dish) were incubated in RPMI-1640 containing 1% FBS overnight and then stimulated for 30 mins with MSP (5nM). Western blot analysis measured the effects of MSP on the phosphorylation levels of RON, Erk1/2, RSK2 and CREB (A). 5637 cells (2 × 106 cells per dish) in RPMI-1640 with 1% of FBS were first treated with Small chemical inhibitors specific to RON (CP-1, 300 nM) (B), Erk1/2 (PD98059, 150 μM) (C), and RSK (SL0101, 50μM) (D) for 12 h, respectively, followed by stimulation with MSP (5nM). Cells were collected 30 mins after stimulation. Phosphorylated RON, Erk1/2, RSK2 and CREB were directly detected by Western blot analysis, respectively. Non-phosphorylated proteins were also determined as the loading controls. (E–H), Quantitative analysis, *P<0.05, **P<0.01 and ***P<0.001 VS. normalized to their own total protein group. Data are shown as mean ± SEM, from one of 3 independent experiments.

Fig 5: RSK2 promotes melanoma cell proliferation. (A) A375 cells were transfected with siNT and siRSK2, the expression of RSK2 protein was analyzed by Western blot and cell viability was measured using CCK-8 analysis. (B) The relative quantification of EdU-positive cells was exhibited. (C) A375 cells were transfected with shNT and shRSK2, the expression of RSK2 protein was analyzed by Western blot and the growth curve was determined. (D) The quantification of relative clone number was exhibited. ∗p < 0.05, ∗∗p < 0.01 vs. the Con group.