Mad-related genes in the human

Resistance to the growth inhibitory effects of TGF-β is common in human cancers. However, the mechanism(s) by which tumour cells become resistant to TGF-β are generally unknown. We have identified five novel human genes related to a Drosophila gene called Mad which is thought to transduce signals from TGF-β family members. One of these genes was found to be somatically mutated in two of eighteen colorectal cancers, and three of the other genes were located at chromosomal positions previously suspected to harbor tumour suppressor genes. These data suggest that this gene family may prove to be important in the suppression of neoplasia, imparting the growth inhibitory effects of TGF-β-like ligands.