In breast cancer cell lines, there is evidence of an anti-proliferative effect of CTR activation (Nakamura et al., 2007; Ng et al., 1983), while in prostate cancer the up-regulation of the CT/CTR axis seems to help the switch of prostate cells towards a malignant phenotype (Thomas et al., 2006, Thomas, Muralidharan & Shah, 2007) stimulating proliferation, metastization and angiogenesis. The gene discussed is CALCR; the disease is breast cancer.