May be a cytokine receptor for GPR15LG. May be a tumor suppressor; together with GPR15LG has a growth inhibitory effect on colon cancer cells which includes G1 cell cycle arrest (PubMed:25351403). May play a role in breast tumorigenesis (PubMed:23131994). {ECO:0000269|PubMed:23131994, ECO:0000269|PubMed:25351403}. This is the function of SUSD2 (sushi domain containing 2, Ensembl gene identifier ENSG00000099994).