PD‐1 blockade increased the fractions of CD4‐c02‐Itgb1 and CD4‐c03‐Il21 in SubQ‐only mice (Figure 3H), in line with the previous notion that tumor‐draining LN could supply T cell pools in tumors.[26, 38] However, in mLNs of CSLT mice, anti‐PD‐1 barely changed the proportions of CD4‐c02‐Itgb1 and CD4‐c03‐Il21 (Figure 3H), suggesting that liver tumors might influence the responses of Tcm and Tfh to PD‐1 blockade in mLNs. Here, IL21 is linked to neoplasm.