Fig. 1

SOX4 promotes breast cancer cell proliferation both in vitro and in vivo. a Western blot analysis of SOX4 expression in three human breast cancer cell lines. Embryonic kidney cell line 293 T with ectopic SOX4 expression (293 T-SOX4) was used as positive control. GAPDH was used as loading control. b Western blot showing SOX4 protein levels in MDA-MB-231-SOX4 cells and SUM149-SOX4 cells as well as the control cells. GAPDH was used as loading control. c and d MTT assay showing cell viability in SOX4-expressing cell lines compared with control. The data are presented as the mean ± s.d. of sextuplicate wells. Unpaired two-tailed t-test: ***p < 0.001. e In vivo tumor growth from SOX4-expressing cells and control cells. 5 × 10⁶ cells were injected into the mammary fat pad of SCID mice. The length a and width b of tumors were recorded weekly. The tumor volume was calculated by the formula of V = ab²/2 (mm³). The data are presented as the mean ± s.e.m. of 6 mice. Unpaired two-tailed t-test: **p < 0.01. f Bioluminescent imaging illustrating tumor growth in vivo. g Western blot showing the SOX4 expression in BT474 cells with individual shRNAs. h Semi-quantitative analysis of western blotting. Unpaired two-tailed t-test: **p < 0.01, ***p < 0.001, ****p < 0.0001. i MTT assay showing decreased cell viability in SOX4-knockdown cells (BT474-14, BT474-16) compared to the control (BT474-NT). j Slower in vivo tumor growth from SOX4 knockdown cells compared to the control cells at different time points. The data are presented as the mean ± s.e.m. of 5 mice. k Bioluminescent imaging showing slower tumor growth with SOX4 knockdown