Active uptake via organic anion transporting polypeptides (OATPs), especially OATP1B3, which are overexpressed in breast, colon, pancreatic, and liver cancers, contributes to a three- to five-fold increase in ICG retention in tumors compared to healthy tissue and persists even after 24–48 h [19,20]. Here, SLCO1B3 is linked to liver cancer.