Sperm-associated antigen 4 protein (SPAG4, also known as SUN4) is a SUN domain containing protein that was originally isolated from the testis []. It binds outer dense-fibre protein Odf1 and localises to microtubules of manchette and axoneme []. SPAG4 was later found expressed ubiquitously in various normal tissues and neoplastic tissues in humans at the mRNA level []. In renal cell carcinoma, SPAG4 is an independent prognostic factor and plays a crucial role in cytokinesis to defend against hypoxia-induced tetraploid formation []. It also promotes renal clear cell carcinoma migration and invasion in vitro [].This entry represents SPAG4 from mammals.
