BRAF and melanoma: However, the loss of both Lkb1 alleles in mice harboring either one Braf‐mutant allele (BrafCA/+) or both Braf‐mutant alleles (BrafCA/CA) promoted a slight decrease in the incidence of melanoma, from 18.1% to 11% and from 31.2% to 12.5%, with an onset of 326 ± 90 and 319 ± 17 days, respectively (Fig. 2A).