Blocking the interaction between FGL1 and LAG3 can enhance the antitumor function of T cells.101 It is interesting to point out that LAG3 is also expressed in Tregs to inhibit proliferation and function.102 Meanwhile, ligation of MHC-II on APCs by Treg-expressed LAG3 also suppresses APCs function.103,104 Therefore, the roles of LAG3 are complex and using LAG3 blockade for cancer immunotherapy needs to be carefully studied to provide clinical benefits. Here, FGL1 is linked to cancer.