The inactivation of COLGALT1 in osteosarcoma cells led to collagen type I accumulation, and cells with inactive COLGALT1 and COLGALT2 genes could not be grown, suggesting that osteosarcoma cell viability and proliferation are impaired by a complete loss of collagen glycosylation (Lee et al., 2015). The gene discussed is COLGALT2; the disease is osteosarcoma.