Hsp90 inhibition abrogates T-cell proliferation and phosphorylation of STAT5, STAT3, Akt, and ERK1,2 in activated primary CD3⁺ T lymphocytes. (A) CFSE dilution after 4 days in T-cell cultures activated either with PHA or CD3/C28 microbeads in control cultures or cultures treated with the Hsp90 inhibitor 17-DMAG. (B) Primary human CD3⁺ T cells were either left untreated (lanes 1,3) or treated with 17-DMAG (lanes 2,4) for 43 hours before activation with CD3/CD28 Dynabeads for 1 hour (lanes 3-4), and analyzed by Western blot. The protein expression levels of phosphorylated (Y694) and total STAT5, phosphorylated (Y705) and total STAT3, phosphorylated (Ser⁴⁷³) and total Akt, and phosphorylated (Thr²⁰²/Thr²⁰⁴) and total ERK1,2 are shown. Staining of β-actin was used as loading control.