Together, the data in Figure 4, Figure 5 and Figure 6 lead us to conclude that: (1) redox modifications of cysteine thiols in the MITF are caused by H2O2 and that these modifications may be reversed or prevented by TR1; and (2) production of mRNA that includes the melanocyte-specific exon 1M requires TR1 in M14 melanoma cells. Here, TXNRD1 is linked to melanoma.