UBE2A and melanoma: Since the TCGA data in Figure 1A revealed significant heterogeneity in RAD6B expression levels and copy number alterations as compared to RAD6A, we performed RT-PCR analysis of RAD6B transcripts amplified from normal melanocytes (HEMa-LP), melanoma lines (A375, A2058, M14), and patient-derived melanoma brain metastasis (Mel-Met-14-089 and Mel-Met-14-108) using RAD6B specific primers that span the entire RAD6B coding region.