Cell denudation and immunostaining. After ten days of culture, cell denudation was carried out by using an extraction buffer. The plates were slightly tilted to aspirate media using a sterile Pasteur pipette and were washed with 2 mL of PBS once. The extraction buffer was prepared with PBS (48.8 mL) containing 0.25% (v/v) Triton X-100 (250 µL), and 10 mM ammonium hydroxide (250 µL). This extraction buffer solution was prewarmed in a 37°C water bath and 1 mL of this solution was then carefully added to each well. The coverslips were gently lifted with a pipette tip and tweezers so that the buffer can reach under them. It was left for 4 min for cell lysis, as confirmed by bright field microscopy (Leica DMI8 epifluorescence microscope). Then half of the buffer was carefully removed using a Pasteur pipette. Approximately 2 mL of PBS without Ca 2+ and Mg 2+ was added to each well. These steps were repeated until no intact cells were seen under the microscope. 10 mL of 10 µg/ mL DNase I solution (Roche) was freshly prepared by adding 10 µL of DNase I stock solution (10 mg/mL) to 10 mL of sterile PBS. 2 mL of this DNase I solution was then added to each well to digest the DNA residues and incubated for 30 min at 37°C. The denuded CDMs were washed with 2 mL of PBS twice.