Similarly, in an in vivo experimental model of metastasis in mice, disseminated human colorectal cancer cells were found to secrete the protein creatine kinase brain-type (CKB) in the liver, where it catalyses the conversion of extracellular ATP and hepatic creatine into phosphocreatine, which is incorporated into metastatic cells via the creatine transporter, SLC6A8. Here, SLC6A8 is linked to colorectal cancer.