A key role of HOX genes in cancer thus seems to be the repression of Fos, DUSP1, and ATF3 expression, which in turn inhibits apoptosis, and correspondingly DUSP1 [14] and ATF3 [15] have both previously been identified as potential tumour suppressor genes in prostate cancer, although the role of Fos in this context is less clear. The gene discussed is ATF3; the disease is prostate carcinoma.