PIK3CA, a PI3/PI4 kinase, phosphorylates PtdIns, PtdIns4P and PtdIns(4,5)P2 with a preference for PtdIns(4,5)P2. Defects in PIK3CA are associated with colorectal, breast and epithelial ovarian cancers.The synthetic peptide used to raise the antibody Cat. No. 200119 is selected from a sequence within the C-term region of human PI3KCA. For blocking experiments, a 10 to 100 fold molar excess to antibody is recommended.