Lack of Hap1 impacts on the intracellular trafficking of Cav1.2-YFP in INS-1 cells. INS-1 cells were transfected with Hap1-siRNA or scramble-siRNA plasmids, together with Cav1.2-YFP. A, FRAP of Cav1.2-YFP trafficking in living INS-1 cells. The images show Cav1.2-YFP fluorescence before and immediately after photobleaching, as well as after 40, 80, and 120 s of recovery in scramble-siRNA- (upper) and Hap1-siRNA (bottom)-treated cells. The initial fluorescence is indicated as 100%. Scale bar, 5 μm. B, FRAP time course from scramble-siRNA (○)- and Hap1-siRNA (●)-treated cells in A. Fits indicate a τ of 20.1 s (scramble) and 34.6 s (siRNA). C, mean time constant τ of scramble-siRNA-treated cells (scramble) or Hap1-siRNA-treated cells (siRNA). Less time is needed for scramble-siRNA cells to get a fluorescence recovery of Cav1.2-YFP compared with Hap1-siRNA-treated cells (**, p < 0.001; scramble n = 25, siRNA n = 27).