PAX3 and melanoma: Consistent with the co-localization of MYSM1 and PAX3 in A375 cells in vitro, in SSM patient samples analyzed, MYSM1+PAX3+ double-positive cells could be found preferably in the tumor cell clusters formed by melanoma cells at the epidermal-dermal junction and in the dermis in the majority of SSM samples analyzed (Figure 6A and 6B).