CX3CR1 and skin cancer: CX3CL1 in the tumor milieu promotes migration of multiple CX3CR1+ tumor types such as breast cancer, prostate cancer, CLL, neuroblastoma, glioblastoma, pancreatic ductal carcinoma (PDAC), colon carcinoma, gastric cancer, skin cancer, lung cancer, osteosarcoma, melanoma, multiple myeloma, and bladder cancer (14–18), and 3.