FGFR3 and seborrheic keratosis: In addition, a phenotype in mice lacking only FGFR3 in keratinocytes was anticipated, as activating mutations in the FGFR3 gene are the cause of the genetic skin disorder acanthosis nigricans and also induce seborrhoeic keratosis and epidermal naevi.10, 11, 12, 13 Here, we show, however, that loss of FGFR3 in keratinocytes does not obviously affect skin morphogenesis, homeostasis or wound repair in mice.