Figure 3
From: Regulation of tamoxifen sensitivity by a PAK1–EBP1 signalling pathway in breast cancer
A PAK inhibitor prevents tamoxifen-induced growth of PAK1-overexpressing hormone resistant cells. (A) Hormone resistant cells overexpress PAK1. Lysates of logarithmically growing parental MCF-7 and LTLT-Ca cells were analysed by western blotting for total PAK1, pPAK or GAPDH as indicated. (B) Threonine phosphorylation of EBP1 in LTLT-Ca and MCF-7 cells. Lysates of logarithmically growing LTLT-Ca or MCF-7 cells were immunoprecipitated with either control IgG or EBP1 antibody before separation of proteins by SDS–PAGE. Proteins were transferred to PVDF membranes, and immunoblotted with antibodies to phospho threonine (pThr) or EBP1 as indicated. (C) LTLT-Ca cells were treated with IPA-3 at the indicated concentrations and cell number determined 7 days later as described in the Materials and Methods. #P<0.01 compared with untreated control. (D) Effect of IPA-3 on PAK phosphorylation. Cells were serum starved overnight in media containing 0.5% FBS with or without 3 μ M IPA-3 as indicated. Cells were then treated with 50 ng ml−1 of HRG for 60 min. Cell lysates were collected and analysed by western blotting for phospho PAK1 and total PAK1 as indicated. (E) LTLT-Ca cells were treated with the indicated concentrations of OHT with or without IPA-3 (3 μ M) and cell number determined at day 7. Representative of five experiments. #P<0.01 compared with untreated control.
