In addition to reproductive organs such as testis, epididymis, ovary, uterus and a variety of germ cells, RGMb also exists in pituitary cells that regulate reproductive organs and some tumour cells derived from the reproductive system, such as Ishikawa, HeLa, MCF-7, etc. In spermatogonia, the expression level of RGMb is positively correlated with gonadotropin (Refs 5, 14). This evidence concerns the gene RGMB and neoplasm.