PTGDR2 and neoplasm: Calcitriol or its analogues downregulated the expression of 4 genes related to the Th1 response in tumour tissue (Ifng (only calcitriol), Socs1, Tbx21 and Fasl) and upregulated 5 genes related to the Th2 response (Ccl11, Ptgdr2, Il9, Asb2 and Il5).