By linear regression methods, both nuclear and cytoplasmic Cks1 correlated with stepwise progression from melanocytic nevi to melanomas in situ, to primary melanomas, to metastatic melanomas (r = 0.34, p < 0.0001 and r = 0.32, p < 0.0001, respectively). This evidence concerns the gene CKS1B and in situ carcinoma.