MAPK3 and breast cancer: Therefore, MDA-231.PIP, MDA-231.C cells, T47D.shPIP, and T47D.shC cells were subjected to cell cycle analysis, which showed the lack of differences between BC cells with different expression levels of PIP, which was further supported by the lack of differences in the expression of such important cell cycle-related proteins as cyclin B1, cyclin D1, and ERK1/2 kinases in lysates of these cells.