TAAR1 and neoplasm: Finally, the addition of an RGDR or iRGD motif at the C-terminus to favor tumor homing and cell internalization, or the Fc domain of human IgG4, that considerably increased the half-life of Tα1, resulted in higher anti-tumor effects compared to Tα1, with higher levels of IFNγ and IL-2 and higher lymphocyte infiltration (33–35).