PLA2G2A and psoriasis: Importantly, the phenotypes of skin cancer and psoriasis in Pla2g2a−/− mice were absent when both genotypes were co-housed in the same cages (which resulted in mixing of the microbiota through coprophagia) or when these mice were housed in a more stringent pathogen-free facility, in which the expression of Pla2g2a in WT mice was reduced and the composition of gut microbiota in the two genotypes became largely even if not solely identical.