CD4 and cancer: The induction of apoptosis by the inhibition of SLC7A5 or dietary L-Leu restriction is a mechanism that might contribute to control CD4 T cell-mediated immune response which has not been described previously, although this effect has been well documented for cancer cells (Choi et al, 2017; Rosilio et al, 2015; Sheen et al, 2011; Yothaisong et al, 2017).