OPA1 and hepatocellular carcinoma: We measured by qPCR the mRNA levels of Exon4b-containing OPA1 isoforms (i.e., isoforms 3, 5, 6, and 8) and those without Exon4b (i.e., isoforms 1, 2, 4, and 7) in 22 paired HCC and adjacent non-tumor liver tissues.