INS and melanoma: The human melanoma A375 cell line, acquired from ATCC, and the human melanoma WM164 cell line, a kind gift from Dr. Meenhard Herlyn (Wistar Institute, Philadelphia, PA), were both cultured in DMEM medium (Mediatech, Inc., VA), supplemented with 10% fetal bovine serum (FBS, Atlanta Biologicals, GA), 1% antibiotic/antimycotic mixture and 5 μg/mL bovine insulin (Sigma-Aldrich, St.