It was found that transfected WtCosmc influenced the activity of T-synthase and core 1- and core 2-derived O-glycans, proliferation and migration of Tn+ tumor cells, and apoptosis induced by Apo2L/TRAIL; however, it did not change the activity of C3GnT and core 3-derived O-glycans. The gene discussed is TNFSF10; the disease is neoplasm.