SPAG9 is a symbol for the gene, Sperm associated antigen 9, in humans. Other names include: C-Jun-amino-terminal kinase-interacting protein 4; JNK-interacting protein 4; Cancer/testis antigen 89; CT89; Human lung cancer oncogene 6 protein; HLC-6; JNK-associated leucine-zipper protein; JLP; Mitogen-activated protein kinase 8-interacting protein 4; Proliferation-inducing protein 6; Protein highly expressed in testis; PHET; Sperm surface protein; Sperm-associated antigen 9; Sperm-specific protein; Sunday driver 1; JIP-4; JNK/SAPK-associated protein; JNK interacting protein; sperm specific protein; c-Jun NH2-terminal kinase-associated leucine zipper protein; Max-binding protein; HLC4; HLC6; JIP4. The encoded protein has an amino acid length of 1321 and a mass of 146.2 kDa. Other isoforms may exist. SPAG9 is a member of the JIP scaffold family. This gene shares homology with other species, including: Mouse.