PIPKIγ expression is required for rapid cell proliferation in breast cancer cells. Lentiviral vector was used to generate the stable knockdown of type I gamma phosphatidylinositol phosphate kinase (PIPKIγ) in breast cancer cell lines as described in "Material and methods". Decreased expression of PIPKIγ was assessed by using PIPKIγ specific antibody. Cells infected with either Control short-hairpin RNA (shRNA) or PIPKIγ shRNA were seeded into 12-well culture plates at a density of 1000 cells/well. Manual cell counting was performed every two days for the eight days. The cell numbers were counted from at least three wells for each cell type and expressed as mean ± standard deviation from one representative experiment. (a) MDA-MB-231 cells. (b) MDA-MB-435S cells. (c) SKBR3 cells.