LCs play a key role in establishment of cutaneous immunity, and participate in squamous cell carcinoma.(12,29) Human dendritic cells including LCs in the skin express H-PGDS, and produce PGD2 in response to various stimuli.(30) Thus it is suggested that the produced PGD2 in autocrine manner in LCs is involved in cutaneous immune system and inflammatory reactions in the skin. This evidence concerns the gene HPGDS and squamous cell carcinoma.