KLK6 and squamous cell carcinoma: Corresponding to its roles in epidermal proliferation and desquamation, KLK6 is overexpressed in skin of patients with hyperproliferative/hyperkeratotic/inflammatory skin diseases including psoriasis, atopic dermatitis and peeling skin syndrome-type B, as well as in premalignant skin lesions and squamous cell carcinomas [21,24–27].