MYCN and hepatocellular carcinoma: With a threshold expression level of MYCN at 1 read per kilobase of exon per million mapped reads (RPKM), 8 out of a total of 25 HCC cell lines were selected as MYCNhigh cells (≥1 RPKM), while the other 17 HCC cell lines were MYCN low expression (MYCNlow) cells (<1 RPKM).