Fig 2: Gene expression analysis of FOSL1 in overexpressed cells. Relative expression levels of FOSL1 (A), SALL2 (B), OLIG2 (C), SOX2 (D), and PUO3F2 (E) in NTERA-2 and HEK293T cells lines after 48 h from transfection with the empty vector or pCMV-FOSL1 vector. Data are presented as mean and standard deviation of the relative expression of each target using the GAPDH as housekeeping gene and the empty vector as calibrator. p value < 0.05, *; 0.005 **; 0.0005 *** (t-test data).

Fig 3: Localization of FOSL proteins and cellular distribution of their binding partners. (A) Following subcellular fractionation of Th0 and Th17 cell lysates (24 and 72 h), IB was performed to detect FOSL1 and FOSL2 in the fractionated samples. LSD1 and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were used to mark the nuclear and cytoplasmic fractions, respectively. Representative blot for three biological replicates is shown. (B) Pie charts showing classification of FOSL1 (left) and FOSL2 (right) interacting proteins based on their cellular localization, using IPA.

Fig 4: Immunohistochemical expression of FOSL1 in AM (A, B) IHC staining images and score quantification of FOSL1 in normal, unicystic, and conventional AMs. Scale bar: 100 μm. ***p < 0.001 by one-way ANOVA. (C, D) IHC staining images and score quantification of FOSL1 in primary and recurrent AM. Scale bar: 100 μm. ***p < 0.001 by Student’s t-test. NS, no significance.

Fig 5: Downregulation of FOSL1 sensitizes to JQ1 treatment.(a) Venn diagram depicting the overlap of significantly differentially expressed genes in Ishikawa cells stably expressing either endometrial (E47K, E50K) or prostate (Y87C, W131G) cancer SPOP MTs without or with JQ1. Overlay is significant p value < 0.05 (Benjamini-Hochberg test). (b) Heat map showing the fold change of the 16 genes included in the intersection of panel a. (c) FOSL1 mRNA (normalized to Cyclophilin) and protein levels of Ishikawa cells stably expressing SPOP-WT and either endometrial or prostate cancer SPOP MTs (n=4). (d) FOSL1 mRNA expression in endometrial30 and prostate31–33 cancer patient datasets stratified accordingly to SPOP status. P value was derived from an unpaired t-test with Welch’s correction. (e) Representative images of human primary endometrial cancer tissues stained for FOSL1 with corresponding expression analysis on human primary tumors stratified accordingly to SPOP mutation status (p value Kendall’s tau-b). Scale bars, 80µm. (f) FOSL1 mRNA and protein expression levels after JQ1 (500nM) treatment in Ishikawa cells stably expressing SPOP-WT and either two endometrial (E47K, E50K) or two prostate (Y87C, W131G) cancer SPOP MTs (n=3). (g) Dose-response curves to JQ1 of Ishikawa-SPOP-Y87C cells upon FOSL1 knockdown (n=3). P value is indicated below the dose-response curves by extra-sum of squares F test. Corresponding WB validation of FOSL1 knockdown. N indicates the number of independent experiments performed. All error bars, mean ± SEM. Statistical significance was determined by unpaired, two-tailed Student’s t-test unless otherwise specified (n.s., non-signicant, *P < 0.05, **P < 0.01, ***P < 0.001).