Mita et al., demonstrated in CD69–/– mice using 4T1-luc2 murine breast cancer models, a significant reduction in tumour growth and metastasis, increased levels of tumour-infiltrating lymphocytes and a significant reduction in T cell exhaustion and enhanced IFN-γ production compared with wild-type controls (Mita et al. 2018). The gene discussed is IFNG; the disease is breast cancer.