RB1 and neoplasm: Although the growth difference in A549 and 12.2 is characterized by a significant delay at G1/S in the latter, we did not find significant changes in gene expression for common G1/S phase regulators HRAS, p19, RB1, TP53, MYC, and CCND1. Also, the increased expression of VEGF in 12.2 cells contrasts with observations from many tissues which show that this gene is up-regulated in tumor cells.