Scientists at the National Cancer Institute developed a cell line designated A549 that was derived from explanted cultures of human lung cancer tissue. The A549 cell line has been tested under the guidance of the United States Food and Drug Administration (FDA) so, under current Good Manufacturing Practices (GMP), these cells may be suitable for use in manufacturing constructs for use in clinical trials. The A549 cell line has also been found to be suitable for adenovirus production, most notably replicating adenovirus constructs that do not require complementation by the viral oncogene, early region 1A (E1A), which is responsible for viral gene transcription. This cell line is further utilized as a negative control in assays to measure the replication of adenoviruses that lack E1A and as a target cell line to detect replication competent adenoviruses (RCA). A549 cells have been well characterized through their use in a wide variety of molecular studies, such as anti-tumor drug permeability and efficacy analysis, infection assays, respiratory immunotoxicity tests, cell senescence studies, and cytokine expression profiling. These cells can also be utilized to study a variety of molecular characteristics for human tumors in culture.