ANPEP and hepatocellular carcinoma: CD13 was found to be a semi-quiescent CSC marker for HCC by Haraguchi, et al. [18] They also demonstrated the efficacy of a CD13 (aminopeptidase N) inhibitor, Bestatin, both in vitro and in vivo [18]; this drug has been approved for the maintenance treatment for acute myeloid leukemia in Japan.