ST18 and neoplasm: Numerous corroborating observations support this possibility, including (1) clonal amplification of tumor cells containing the L1 mutant ST18, (2) ectopic ST18 transcription and translation in tumor not seen in adjacent nontumor liver or control liver, (3) consistent ST18 expression in transformed liver cancer cell lines, (4) frequent amplification of ST18 in HCC nodules taken from Mdr2−/− mice, and (5) induction of ST18 transcription in those animals.