(A) Growth curves of primary melanocyte cultures from mice of indicated genotypes are illustrated. Cells were treated with or without 4-OHT at 20 days postisolation to activate CRE recombinase, and cell numbers were counted during serial passage. At least three primary lines were generated for each group, and representative results are shown. Error bars show SD.
(B) Changes in pigmentation of representative 8-week-old adult mice of the indicated melanocyte-specific genotypes are shown. Mice without K-Ras activation exhibit normal pigmentation, whereas K-Ras-expressing cohorts showed pigmented macules on the paws and tails, with increasing hyperpigmentation noted with concomitant Lkb1 and/or p53 loss.
(C) Representative mice with melanocyte-specific loss of Lkb1 and K-Ras activation show increased and heterogeneous coat color pigmentation compared to Lkb1-intact mice.
See also Figure S1.