PSAP and psoriasis: Comparison of the human epithelial cell line HaCaT with “psoriasis-like” inflammation phenotype with control keratinocytes cultured in medium containing a low concentration of Ca2+ ions (≤0.1 mM) showed no significant changes in gene expression, with the exception of HYAL4, PSAP (down-regulated), and SPHK1 (up-regulated).