PTGS2 and cancer: mRNA expression levels of CYP27B1, CYP24A1 and COX-2 but not of the VDR were significantly higher in cancerous lesions compared to adjacent mucosa (Figure 2), but varied in different directions during progression from low to high grade malignancy: Compared to the adjacent mucosa, CYP27B1 expression was four times higher (p < 0.001) in both low and high grade cancers (Figure 2A).