HACE1 and breast cancer: HACE1 was found to undergo allelic loss in breast cancer as well as many other cancers while hypermethylation of the HACE1 promoter has also been observed.13, 38, 39, 40 Gene inactivation of Hace1 in mice results in spontaneous cancers after long latency in multiple sites including the breast, further supporting the notion of HACE1 being a breast tumor suppressor gene.13