Immunofluorescence staining assays were performed as we described previously . Cells were incubated overnight with the primary antibody against α-SMA (ab5694) and desmin (ab15200) (1 : 50 dilution; Abcam, USA) at 4°C. The cells were washed three times with PBS (5 min each) and then incubated in the dark for 1 h at room temperature with Alexa Fluor 488 and 550 conjugated goat anti-rat secondary antibody (1 : 200 dilution; ab150157 and ab150083, Abcam, USA). Nuclei of cells were stained with 4′,6-diamidino-2-phenylindole (DAPI) (Sigma-Aldrich, USA). Images were obtained using a Zeiss LSM 510 META Confocal microscope using 20x/0.5 w and 40x/1.2 w objectives.