**1. Introduction**

The carcinogenesis and progression of hepatocellular carcinoma (HCC) are complicated processes which evolve through distinct stages associated with cumulative genomic alterations, which result in deregulation of proliferation, metastasis and recurrence, leading to poor prognosis. Despite the fact many new therapeutic and diagnostic strategies for cancer have been developed in recent years, the cure rate for HCC has not satisfactorily improved and biomarkers currently used for HCC diagnosis are not satisfactory in either their specificity or sensitivity.

More than one thousand cancer-associated genes and proteins have been identified, but the pathogenesis of hepatocellular carcinoma is still incompletely understood. Identifying the as yet unknown pivotal genes and proteins will be critical for early diagnosis, effective monitoring and novel therapies for this highly aggressive cancer. In previous work we cloned and identified a novel HCC-associated gene (lysosomal protein transmembrane 4 beta, *LAPTM4B*). Its complementary mRNA is highly expressed in the vast majority of HCC samples as compared with paired noncancerous liver from the same patient (PNL), fetal liver, and normal liver (Shao et al., 2003). Over our past decade studies have demonstrated that the *LAPTM4B* gene and the LAPTM4B-35 protein which it encodes would be pivotal diagnostic biomarkers and therapeutic targets for hepatocellular carcinoma.
