This expression pattern suggests that KC4 contains keratinocytes of the different anatomical structures of the hair follicle in line with KC4 cluster’s position next to the BCC keratinocytes (KC3) and the presence of PTCH1/2 and GLI1/2 expressing cells (Figs. 2C and S2A-B). The gene discussed is PTCH1; the disease is skin basal cell carcinoma.