PDX1 and melanoma: To examine whether targeting PIKfyve induces MHC-I surface expression, we first knocked out Pikfyve in different murine cancer cell models—KPC1361 derived from a pancreatic tumor of a genetically engineered mouse model (LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1-Cre) and the melanoma model B16-F10 (Fig. 1A).