In addition, we and others have confirmed the existence of proliferative cells in K14ΔNLef1 sebaceous tumors by showing Ki67 expression (Niemann et al, 2002), BrdU incorporation (Niemann et al, 2007), and isolating tumor‐propagating cells that form secondary tumors in serial transplantation assays (Petersson et al, 2015). This evidence concerns the gene MKI67 and neoplasm.