Furthermore, it will be important to explore whether Ct-OATP1B3 mRNA can be detected in blood, because it has become evident that serum exosomes secreted from cancer cells contain cancer cell–derived molecules [24], such as the tumor-specific mRNA splicing variant detected in serum exosomes obtained from several glioblastoma patients [25]. The gene discussed is SLCO1B3; the disease is cancer.