PHGDH and Hand-foot syndrome: With a 30-day pre-induction, skin from PHGDHtetO;Dct-rtTA mice displayed melanin granules in early anagen HFs with similar percentages as those observed in mice with a Rosa26-M2rtTA allele (Fig. 3a-b), suggesting that the PHGDH-dependent presence of melanin in early anagen HFs is a melanocyte-autonomous event.