PTEN stabilizes MTSS1 expression levels. (A) MTSS1 protein level is positively regulated by PTEN in S63 fibroblast cells. PTEN overexpression increases MTSS1 protein level, and PTEN knockdown decreases MTSS1 protein level. Cell lysates of S63 cells, which were transfected with control, PTEN, or shPTEN, were analyzed by Western blot. MTSS1 levels were normalized against β-actin. (B) PTEN increases MTSS1 stability in S63 cells. S63 cells stably expressing vector or PTEN were treated with CHX (20 μg/ml) for indicated times. Endogenous MTSS1 protein levels were determined. Relative MTSS1 levels were normalized against β-actin. In (C) and (D), the same assays were carried out in NIH3T3 fibroblast cells and showed similar results. Data are represented as mean ± SEM. *P value < .05, **P value < .001.