We performed a functional genetic screen to find novel antiapoptotic genes that are under the regulation of the oncoprotein c-Src. Several clones were identified, including subunit S5a of the 26Sproteasome. We found that S5a rescued Saos-2 cells from apoptosis induced by Src inhibitor 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]pyrimidine (PP1).