ABCG2 and melanoma: Chromatin immunoprecipitation (ChIP) using anti-SOX2 antibody followed by qPCR revealed SOX2 occupancy in the proximal promoter region of ABCG2, with a 2- to 4-fold enrichment in SOX2 signal over ChIP with nonspecific IgG in two different melanoma cell types (p < 0.05) (Fig. 7D).