Ready-to-use ELISA kits are available for the detection of RSPONDIN, an alias of the protein, R-spondin 1. The official gene symbol is RSPO1. The protein, with a mass of 29 kDa and length of 263 residues, is reported to be nuclear and secreted. It is a member of the R-spondin family and may be known by other names, including: RSPO, CRISTIN3, roof plate-specific spondin-1, and R-spondin homolog.