In a study by Curiel et al. (2004), tumor Tregs with high expressions of CCR4 interacted with CCL22 or CCL17 secreted by tumor cells or TAMs to facilitate their recruitment into the TME (Iellem et al., 2001; Curiel et al., 2004; Dadey et al., 2020). Here, CCR4 is linked to neoplasm.