TPA and SCF inhibit the growth of some metastatic melanomas (Hsu et al., 2000; Zakut et al., 1993), and some immortal VGP lines grow in simpler media than ours (Herlyn et al., 1985a; Hsu et al., 2000; Pope et al., 1979; Semple et al., 1982). This evidence concerns the gene KITLG and melanoma.