TCF7L1 and skin basal cell carcinoma: By immunohistochemistry, both Tcf7l1 and LCN2 were strongly expressed in psoriasis vulgaris, verrucous epidermal nevus, condyloma acuminatum and SCC (Broders’ grade I) while negative or slight expression was seen with normal skins, seborrheic keratosis, Bowenoid papulosis and basal cell carcinoma (BCC) (Figure 1a).