Sub-cellular localization of Hck and p73α. (A) Cos1 cells transiently transfected with p73α or Hck and p73α were fractionated into nuclear and cytosolic fractions and analysed by immunoblotting for pTyr, p73 and Hck. The purity of nuclear and cytosolic fractions was confirmed by immunoblotting for PARP and α-tubulin. (B) Endogenous Hck in HL-60 cells localizes to both cytosolic and nuclear fractions. HL-60 cells were fractionated into nuclear and cytosolic (post nuclear fraction) fractions and immunoblotted using Hck antibody. The purity of fractions was confirmed by immunoblotting with PARP and Calnexin. WCL indicates whole cell lysates. (C) Localization of endogenous Hck in the nucleus by immunostaining. HL-60 cells were immunostained with Hck antibody after 24 hours of differentiation by TPA (10 ng/ml) and analysed by confocal microscopy. The image shown is the central section passing through nucleus. The cells were also stained without primary antibody, which served as a control.