TMEM176B knockdown suppressed MDA-MB-231 and Mvt1 tumor growth in vivo. (A) Growth charts of MDA-MB-231 control (Scrb), and TMEM176B-silenced (176Bsh1 and 176Bsh2) tumor xenografts in the Rag1−/− female mice (n = 6 mice per group). (B) Tumor weight at the end of the study. (C) Growth charts of Mvt1 control (Scrb), and Tmem176B-silenced (176bsh1 and 176bsh2) syngeneic tumors in the FVB/n female mice (n = 5–7 mice per group). (D) Tumor weight at the end of the study. Data are presented as means ± SEM. Differences between groups were evaluated by the one-way ANOVA test with the Bonferroni post-hoc test. ** or ## p < 0.01, *** or ### p < 0.001. (Scrb vs. 176bsh1 #; Scrb vs. 176bsh2 *) tumors compared with controls (Figure 2A,B). We next examined the growth of Mvt1 tumors with TMEM176B silencing in FVB/N mice, and we found that TMEM176B-silenced tumors displayed more than an 80% reduction in growth compared to the Mvt1 control tumors (Figure 2C,D). These findings suggest that TMEM176B expression on breast cancer cells may play an important role in tumor growth.