The overexpression of the antiapoptotic gene Bcl-2 has been previously shown to protect cells from undergoing apoptosis during exposure to environmental stress. There is strong evidence that, in addition to its well-known effects on apoptosis, Bcl-2 is involved in antioxidant protection and regulation of cell cycle progression. To determine if the overexpression of Bcl-2 could improve the process of adaptation to suspension and protein-free growth environments, we have studied the growth and viability of anchorage-dependent Chinese hamster ovary cell lines that differ only in there expression of Bcl-2. In addition, we examined the effect of combining Bcl-2 and p21(CIP1) expression during adaptation to suspension and protein-free environments. The results of this study provide evidence of a clear reduction in the overall time required for the process of adaptation to both suspension and protein-free environments in Bcl-2 expressing cultures and that through the combined expression of p21(CIP1) and Bcl-2, it is possible to further reduce the time. The Bcl-2 results support the well-demonstrated concept that this protein plays an important role in apoptotic signaling pathways and suggest that it may also provide more diverse functions beside its death-inhibiting role.