HMOX1 and lung carcinoma: Overexpression of enzymatically active HO-1 in A549 lung carcinoma cells blocks tumor xenograft growth as compared to xenografts established from A549 cells stably transfected with control empty vector (control vector: 406 ± 58 mm3, HO-1: 134 ± 28.4 mm3, p < 0.05).