TNF and Hand-foot syndrome: In the absence of KRT17, keratinocytes are more susceptible to TNFα-mediated apoptosis and HFs prematurely undergo the anagen-catagen transition, demonstrating the critical role for a single keratin, KRT17. Further support for the role of KRT82 in hair loss is seen in the Sox21 knockout (Sox21−/−) mouse model of cyclic alopecia that demonstrated altered keratin expression signatures, including a prominent reduction of KTR82 in the hair shaft cuticle25.