Indeed, certain SLC proteins have a role in the cellular absorption of cancer medicines such as chemotherapeutics and targeted therapies, and various therapeutic methods targeting SLC family members have been found and are being tested in cancer clinical trials (César-Razquin et al., 2015; Nyquist et al., 2017; Rives et al., 2017; Panda et al., 2020). Here, CCL21 is linked to cancer.