MAPK6 and breast carcinoma: To further assess MAPK6 function in human cancer cells, we next examined the impact of Dox-inducible MAPK6 overexpression in several diverse human cancer cell lines with low to high endogenous levels of MAPK6, including the prostate cancer PC3 and DU145, ovarian cancer OVCA433, breast cancer SUM159, and non–small cell lung cancer H1299 cells (Fig. 1E).