KISS1 and RHOC mRNA expression in a panel of RGP, VGP and metastatic melanoma cell lines. Comparison of the expression levels of the KISS1 metastasis suppressor gene (A) and the small GTPase RHOC (B) among melanoma cell lines of different stages of tumor progression supported the selection of WM1552C cell line as the RGP representative for suppression subtractive hybridization against a pool of metastatic cell lines. Samples of 20 μg of total RNA from different melanoma cell lines were submitted to electrophoresis in 1% agarose-formaldehyde gel and transferred to nylon membrane (Hybond N, Amersham Pharmacia Biotech) by standard methods. Fragments of the indicated genes were radiolabeled with [α-32P]-dCTP by random-priming (Rad-prime kit, Invitrogen) and used as probes for Northern blot hybridization. In order to correct for loading differences, after stripping, the blots were probed with a ACTB (β-actin) cDNA fragment.