GPR68 and Merkel cell skin cancer: However, GPR68 is expressed in numerous human tumors, including PDAC tumors and primary PDAC CAFs [24], gastrointestinal stromal tumors (GIST) and appendiceal tumor CAFs [24], colon cancer CAFs [60], anaplastic thyroid cancer (FRO) cells [26], osteosarcoma MG63 cells [22], medulloblastoma tissue [61] and medulloblastoma cell line DAOY [62], Merkel cell carcinoma (MCC), dermatofibrosarcoma protuberans (DFSP), atypical fibroxanthoma (AFX), and pleomorphic dermal sarcoma (PDS) [63].