CREBBP and lung carcinoma: To determine whether CBP specifically binds to hTERT promoter through serving as a transcriptional co-activator and interacting with the transactivators which bind to the hTERT promoter and differentially activates hTERT expression in lung cancer cells, we analyzed the direct interaction of CBP with two transactivators Sp1 and AP-2 bound to hTERT promoter by a co-immunoprecipitation assay.