CCND1 and breast cancer: Furthermore, previous association studies have identified susceptibility alleles for breast cancer in two genes, TGFBR2 (transforming growth factor beta receptor II) (Michailidou et al. 2013) and CCND1 (cyclin D1) (French et al. 2013), which may be involved in immune regulation in cancer patients (Gabrilovich and Nagaraj 2009; Krieg and Boyman 2009), including those with breast cancer.