PIK3CA and Merkel cell skin cancer: Importantly, aberrations in the PI3K/AKT/mTOR pathway (AKT2, FBXW7, NF1, PIK3CA, PIK3R1, PTEN or RICTOR) were also commonly seen in Merkel cell carcinomas (9/17 [53%]) (Tables 1 and 2, Figure 1).