Organotypic raft cultures of HPV16 and HPV18 immortalized keratinocytes. After culturing in the presence or absence of PI3-kinase inhibitor LY294002, following siRNA transfection (p53) (nontarg: non-targeting siRNA; siPIK3CA: PIK3CA specific siRNAs) and upon PIK3CA overexpression (p52-56) (cPIK3CA). (A) H&E staining showing raft culture morphology. (B) Double immunofluoresence probing performed on sections of the same cultures for p-PKB/AKT (green), Ki-67 (red) and DAPI (blue) and (C) for p-PKB/AKT (green), CK10 (red) and DAPI (blue). P: passage.