GFP-fusion proteins maintain their distinct localization in cells lacking endogenous filamin and α-actinin. The GFP probes were expressed in a cell line lacking both endogenous filamin and a-actinin and the localization examined. In each case, the results obtained were similar to the localization found when probes were expressed in wild-type cells. GFP-FLN maintains its cortical localization in the double mutant while GFP-αA is found in new protrusions but not in the cortex (Panels A and C). The same results were found for the ABD's of both proteins (Panels B and D).