SLCO1B3 and colorectal carcinoma: However, a form of alternative splicing of this carrier, lacking the first 28 amino acids, called cancer-type OATP1B3, is markedly expressed in colon cancer tissue [24,25], which could affect the sensitivity of tumor cells to OATP1B3 substrates and has been associated with poorer clinical response to irinotecan therapy in CRC patients [26].