Six different SLCO/OATP (OATP1A2, OATP1B1, OATP1B3, OATP2B1, OATP3A1, OATP4A1) are known to effectively transport E1S (Mueller et al., 2015), although their expression and action in CRC is poorly defined. Here, SLCO4A1 is linked to colorectal carcinoma.