CT120A gene was isolated from chromosome 17p13.3 by using positional cloning and RACE by our laboratory. Here, we reported the evidence that CT120A protein was a potential molecular target for treatment of lung cancers. CT120A was overexpressed in 15 cases of the 16 primary lung cancer specimens. Knockdown of CT120A by small hairpin RNA in the human lung adenocarcinoma cell line SPC-A-1 cells resulted in a reduced cell growth rate in vitro and decrease of the capacity for anchorage-independent growth and tumorigenicity in nude mice. The suppression of CT120A expression also sensitized cells to ultraviolet-induced apoptosis. Atlas cDNA expression array revealed that the expressions of several apoptosis- and growth-associated genes were altered underlying the molecular mechanisms of these cell biological behaviors. These results suggested that CT120A was a novel lung cancer-related gene and CT120A might be a potential target for therapeutic anti-cancer drugs.