NCK2 and metastatic melanoma: To assess whether increased expression of Nck2 protein levels in human metastatic melanoma cells correlates with upregulated transcription of Nck2 gene, we compared Nck1 and Nck2 mRNA levels in three human melanoma cell lines at different stages of progression and in human primary melanocytes (HEM) by performing RT-PCR using Nck isoforms specific primers.