In the most recent study of PD-1 ubiquitin ligase, Liu et al. employed bioinformatics and biochemical research techniques to identify a new E3 ligase, FBW7, which targets PD-1 Lys233 residues at K48, facilitating the degradation of PD-1 and augmenting in vivo anti-tumor immunity [39]. Here, PDCD1 is linked to neoplasm.