CCL21 and cancer: A large number of studies have demonstrated that chemokines are involved in the progression, migration, and survival of cancers, such as CXCL12 (ENSG00000107562), CCL21 (ENSG00000137077), and especially CCL19 (ENSG00000172724), which is associated with progression of cervical cancer (Teicher and Fricker, 2010; Xiong et al., 2017; Zhang et al., 2017).