Figure 1. A) Sequence comparison of the ErbB-2 region responsible for binding to Hsp90 and the corresponding region in LIMK1 and LIMK2. Identical (cyan shade) or conservatively substituted residues (yellow shade) are shown boxed. The asterisk denotes the glycine residue implicated in interaction of ErbB-2 with Hsp90. The numbers represent the position of the proline residue in LIMK1 and ErbB-2. B–E) Inhibition of Hsp90 enhances the degradation of LIMK1 and LIMK2 and down-regulates p-cofilin levels. 293T cell lysates incubated with 1 µM 17-AAG or 1 µM Radicicol (Rad) for 2 to 24 h were subjected to immunoblotting with anti-actin rat anti-LIMK1 (B) or anti-LIMK2 (C) mAbs and rabbit antiactin Abs for loading control. D) Summary of the data presented in (B) and (C). E) Cell lysates of 293T incubated for 24 h with 1 µM 17-AAG or Radicicol were subjected to Western blotting and probing with anti-phospho-cofilin (p-cofilin), and reprobing with anti-cofilin Abs. The numbers below represent the relative amount of p-cofilin after treatment with the inhibitors where its level in nontreated cells is set to 1.0.