The pro‐tumoral effect of SLC3A2 overexpression was also abolished in PTCL cells cultured in medium lacking arginine (Figure 4K and Figure S4G, Supporting Information); however, adding arginine to the medium fully rescued the SLC3A2 overexpression‐induced decrease in PTCL cell proliferation. Here, SLC3A2 is linked to mature T-cell and NK-cell non-Hodgkin lymphoma.