KAAG1, kidney-associated antigen 1, or RU2AS (RU2 antisense gene protein) has been found in mammals. It is expressed in testis and kidney, and, at lower levels, in urinary bladder and liver. It is expressed by a high proportion of tumours of various histologic origin, including melanomas, sarcomas and colorectal carcinomas.
Jiyao W et al.(2023). "The conserved domain database in 2023.",