Fluorescence microscopy. Stained cells or tissue sections were mounted on
slides in 90% (vol/vol) glycerol–10% PBS or Vectashield antifade medium
(Vector Laboratories, Burlingame, CA) with coverslips. Samples were examined under a Nikon E-800 epifluorescence microscope equipped with a
cooled charge-coupled device (CCD) camera. Images were captured and
processed with SimplePCI image analysis software (Compix, Inc., Cranberry
Township, PA).