Fig. 4. MAPK4 promotes TNBC xenograft growth in vivo.

Dox-induced knockdown of MAPK4 inhibits a MDA-MB-231 and b HCC1937 xenograft growth in SCID mice. c Dox-induced overexpression of MAPK4 promotes SUM159 xenograft growth in SCID mice. 2 × 10⁶ of engineered MDA-MB-231 or HCC1937 cells with Dox-inducible knockdown of MAPK4 (ishMAPK4) or control (iNT), or engineered SUM159 with Dox-inducible ectopic expression of MAPK4 (iMAPK4) or control (iCtrl), were injected into the mammary fat pad of female SCID mice (iCtrl or iNT on the left side; iMAPK4 or ishMAPK4 on the right side). Mice began receiving Dox (0.2 mg/ml for SUM159 xenografts and 4 mg/ml for MDA-MB-231 and HCC1937 xenografts) in 1–10% sucrose in drinking water on the day of xenograft implantation. Tumors were harvested as indicated. d Western blots and e Soft-agar assays on engineered MCF10A cells with Dox-inducible MAPK4 expression. Dox concentration used are as indicated in (d) and 0.5 μg/ml in (e). Bar: 500 μm. Data are mean ± SEM. P values determined by unpaired two-tailed Student’s t test. Data are representative of at least three independent experiments. Source data are provided as a Source data file.