To this end, we incubated 5 MCC cell lines (WaGa, MKI-1, MKI-2, MCC13, UISO) for 24, 48 and 72 hours with the PI3K inhibitor LY-294002 at different concentrations (range 12.5–50 μM) and subsequently analyzed the cells using the MTS assay. This evidence concerns the gene PIK3CA and Merkel cell skin cancer.