DDRGK1 and diabetes mellitus: The UFM1-activating enzyme (UBA5), UFM1-specific ligase (UFL1), UFM1-conjugating enzyme (UFC1), UFM1-binding protein (UFBP1), and UFM1-specific proteases (UFSP2) together constitute the UFMylation system, which is a kind of ubiquitination modification to which numerous human diseases are linked, including ischemic heart diseases, diabetes, atherosclerosis, hip dysplasia, schizophrenia, and cancer [37].