FKBP51 lacking the TPR sequence continues to promote cell survival.

UT-7/Mpl cells were infected with a retrovirus encoding both the FKBP51 mutant (FKBP51-414) and EGFP or a control retrovirus encoding EGFP alone. EGFP⁺ cells were sorted and permanent cell lines were obtained in the presence of GM-CSF. (A) At 24 hours, UT-7 cell survival in GM-CSF after daunorubicin treatment. Cells were deprived in GM-CSF and living cells were counted at day 2 by the trypan blue exclusion test or MTT test. Results from the trypan blue exclusion test are presented. EGFP⁺ cells and the wild-type UT-7 cells have similar survival, whereas UT-7/Mpl 414 cells stay alive for up to 5 days after cytokine deprivation (P = .00037). (B) UT-7/Mpl cell survival in cytokine-free medium. Cells were deprived in GM-CSF and living cells were counted at day 2 by trypan blue exclusion test or MTT test. Results from the trypan blue exclusion test are presented. EGFP⁺ cells and the wild-type UT-7 cells have similar survival whereas FKBP51 overexpressing UT-7 stay alive for up to 5 days after cytokine deprivation.