Fig 2: CAPG-171aa interacts with STK38 activating the downstream MEK1/2-ERK1/2 pathway via MEKK2. (A) MDA-MB-231 and MDA-MB-468 cell lysates were IP with anti-MEKK2 antibody followed by detection with anti-MEKK2, STK38, and SMURF1 antibody. (B) MDA-MB-231 and MDA-MB-468 were transfected with CAPG-171aa-FLAG. Whole-cell lysates were IP with anti-SMURF1 and IgG antibodies followed by detection with anti-FLAG, STK38, SMURF1, and GAPDH antibodies. (C-D) Before being treated with MG132, MDA-MB-231, and MDA-MB-468 were transfected with CAPG-171aa-FLAG and circCAPG KD plasmids. Ubiquitination and protein expression levels of MEKK2 were assayed in CAPG-171aa OE (C) and circCAPG KD (D) MDA-MB-231 and MDA-MB-468. (E) Ubiquitination and protein expression levels of MEKK2 were assayed in circCAPG KD MDA-MB-231 and MDA-MB-468 through pulse-chase experiments with cycloheximide. (F) IB of MEKK2, p-MEK1/2, MEK1/2, p-ERK1/2 and ERK1/2 in circCAPG KD MDA-MB-231 and MDA-MB-468. (G) IB of p-MEK1/2, MEK1/2, p-ERK1/2 and ERK1/2 in OE STK38 MDA-MB-231 and MDA-MB-468. (H) IB of MEKK2, p-MEK1/2, MEK1/2, p-ERK1/2 and ERK1/2 in CAPG-171aa, OE-STK38 and OE-STK38/CAPG-171aa transfected MDA-MB-231 and MDA-MB-468. All data were representative of at least three biological replicates and shown as mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001