Genetically depleting PPARα in mice, pharmacologically inhibiting C24:4 (n-6)-induced PPARα in the nucleus or directly suppressing PPARα activity effectively attenuates PLA2G16-C24:4 (n-6) axis-based immune dysfunction of CD8<sup>+</sup> T cells and their according anti-tumor activities. This evidence concerns the gene PLAAT3 and neoplasm.