Ad5/3-D24-GMCSF induces cell killing and expression of functionally active GMCSF in vitro. Viability of (a) MDA-MB-436 and (b) A549 cells after infection with Ad5luc1, Ad5wt, and Ad5/3-D24-GMCSF. (c) GMCSF secretion by A549 cells after infection with 100 VP/cell Ad5/3-D24-GMCSF. (d) TF1 cells, whose viability is dependent on functional human GMCSF (hGMCSF) were cultured in the presence of 2 ng/ml hGMCSF or indicated amount of filtered supernatant from Ad5/3-D24-GMCSF-infected cells. Normal growth media was used as negative control. Viability of cells was determined after 5 days; viability of cells with commercial hGMSCF was set as 100%. hGMCSF, human granulocyte–macrophage colony–stimulating factor; VP, virus particles.