CXCR4 and cancer: AFP can be used to target metastatic cancer in the liver, in addition to gamma‐glutamyl transpeptidase (γ‐GT) and alkaline phosphatase (ALP).[69] Later studies expanded upon this to develop a 4‐organ MoC platform investigating lung cancer metastasis to the brain, bone, and liver.[247] The platform effectively recapitulated cancer cell migration and colonization at distant organs, as demonstrated by the over‐expression of AFP, RANKL, and CXCR4 protein in liver, bone, and brain cells.