The current study has demonstrated that the kinase activity of HPK1, and not the potential scaffolding function of the protein, plays a key role in the anti-tumor immune response, consistent with previous findings of HPK1 as a negative regulator of TCR-induced T-cell activation and as one of the molecules that maintain peripheral tolerance as revealed with HPK1 KO models [5]. This evidence concerns the gene MAP4K1 and neoplasm.