PMEL and melanoma: There was no evidence of MLANA or PMEL expression in the parent tumor, the cell line derived from the tumor or normal human Schwann cells [defined by RPKM (reads per kilobase of transcript per million reads mapped) values of less than 0.3, which is well below the cut-off for an expressed gene and 15- to 100-fold lower than what we found in normal skin or melanomas, respectively (Supplementary Fig. S1a)].