KRT15 and sebaceous gland neoplasm: Astonishingly, expression of mutant Lef1 was higher in CD34+/Itga6high SCs from K14ΔNLef1 mice (Supplementary Fig. 4e) indicating that lower expression levels of mutant Lef1 driven by the K15 promoter allow for initiation of sebaceous tumours, which differ with respect to morphology, differentiation and aggressive growth.