The expression of POMT1 and POMT2 genes, which encode protein O-mannosyltransferases 1 and 2, two enzymes that act by forming a heterocomplex to carry out the first step in the O-mannosyl glycosylation of α-DG using dolichol-phosphate-mannose as a donor [129, 130], has been analyzed in clear cell carcinoma biopsy samples, with the result that both genes were underexpressed (by ‒ 1.82- and ‒ 1.27-fold, respectively) [76]. Here, POMT1 is linked to clear cell adenocarcinoma.