BCL2 and neoplasm: In addition, unlike Bcl-xL, another Bcl-2 family anti-apoptotic protein, Mcl-1, is decreased in tumor tissues and cell lines in comparison with that in normal liver tissues and cells, of which underlining reason and function remains further study; Bcl-2 protein expression is undetectable in either liver tumor or normal samples, which is in agreement with reports that Bcl-2 is rarely expressed in liver tumor cells [38], [39].