The membrane traffic system has been recognized to be involved in carcinogenesis 
and tumor progression in several types of tumors. α-taxilin is a newly 
identified membrane traffic-related molecule, and its up-regulation has been 
reported in embryonic and malignant tissues of neural origin. In the present 
study, we analyzed the expression of α-taxilin in relation to 
clinicopathological features of hepatocellular carcinomas (HCC) and 
proliferative activity of the tumor determined by proliferating cell nuclear 
antigen labeling index (PCNA-LI). Twenty-nine surgically resected nodules of HCC 
(8 well-, 11 moderately-, and 10 poorly-differentiated) were studied. Fifteen 
cases showed 'strong staining', while 14 cases showed 'weak staining' for 
α-taxilin. A significantly higher expression of α-taxilin was observed in 
less-differentiated (p=0.005), and more invasive (p=0.016) HCCs. The 'strong 
staining' group showed significantly higher PCNA-LI than the 'weak staining' 
group (the medians of PCNA-LI were 59.4% vs. 14.4%, p<0.0001). We also evaluated 
the expression of α-taxilin in hepatoma cell lines (PLC/PRF/5, Hep G2 and HuH-6) 
in association with cell proliferation. The expression levels of α-taxilin 
protein were correlated with their growth rates. In conclusion, the expression 
of the α-taxilin protein was related with an increased proliferative activity 
and a less-differentiated histological grade of HCC. α-taxilin may be involved 
in cell proliferation of HCC, and its expression can be a marker of malignant 
potential of HCC.