CDK6 and skin neoplasm: - effective ATP-competitive CK1 inhibitor (IC50 values of 44 nM for CK1δ and 260 nM for CK1ε)- EC50 value below 100 nM estimated in a MTT assay against human melanoma cell line A375- a binding assay analysis of 442 kinases showed that only CK1δ and CK1ε are strongly inhibited- reduction of the activities of CDK6/cyclin D3, CDK6/cyclin D1, CDK4/cyclin D3, CDK4/cyclin D1, and FLT3 (IC50 values between 368 and 3,000 nM)- decrease of TPA-induced skin tumor formation in carcinogen-initiated mouse skin cells, most likely by the inhibition of the Wnt/β-catenin signaling