TFE3 and melanoma: While MITF-M, the major isoform in melanoma/melanocytes, is constitutively localised in the nucleus, the localisation is not regulated by mTORC1, unlike the other MITF isoforms and TFEB, and does not change after SB202190 or BIRB796 treatment; it forms heterodimers with the other isoforms and with TFEB, TFEC and TFE3 [51,52].