MYC and acute myeloid leukemia: At the same time, shRNA-Tsc2 + Cdkn2a spheres also exhibited evidence of an AML or melanocyte-like phenotype as shown by immunoreactivity for the AML markers PMEL, CATHEPSIN K, MiTF and MART-1 (Fig. 3d), expression of MiTF and CATHEPSIN K by western blotting (Supplementary Fig. 9a) and upregulation of Tyrp1 gene expression in comparison to non-sphere populations or to Myc/Trp53∆/∆ sphere populations (Supplementary Fig. 9b).