EpoRm transduces stronger proliferation and survival signals than EpoR. (A) Flow cytometric contour plots illustrate phosphorylation of STAT5 in T cells transduced with EpoR, EpoRm, or GFP only after stimulation with Epo (10 IU/mL) for 15 minutes. (B) Percentage of GFP⁺ cells expressing pSTAT5 in T cells transduced with EpoR, EpoRm, or GFP only after stimulation with 10 IU/mL Epo or treated with 10 µM ruxolitinib before Epo stimulation. Each symbol represents results of 1 experiment. ****P < .0001; **P < .01. (C) Flow cytometry dot-plots illustrate cell cycle analysis of T lymphocytes transduced with EpoR, EpoRm, or GFP only, unstimulated (top row) or stimulated with 10 IU/mL Epo (bottom row) after 3 days of culture in cytokine-free medium. DNA content, detected by FxCycle staining, is shown on the x-axes; DNA synthesis, shown by 5-ethynyl-2′-deoxyuridine (Edu) incorporation, is shown on the y-axes. Edu⁺ cells are shown in red, with their percentage. (D) Survival of T lymphocytes transduced with EpoR, EpoRm, or GFP-only cultured in absence of exogenous cytokines (no Epo) or in presence of Epo (10 IU/mL) for 3 weeks. Symbols indicate mean (± SD) percentage of cell recovery relative to the number of input cells in triplicate measurements. ****P < .0001; **P < .01; *P = .01. (E) Percentage of T-cell recovery relative to input cells after 6 to 8 days’ culture with or without 100 IU/mL IL-2 and/or 10 IU/mL Epo. Each symbol indicates measurements with T cells of 1 of 4 donors (mean of 3 measurements for 3 donors, and 1 measurement for 1 donor). *P = .02. (F) Survival of T lymphocytes transduced with EpoR, EpoRm, or GFP only cultured with 100 IU/mL IL-2 in the absence or presence of Epo (10 IU/mL). Percentage of T-cell recovery relative to input cells at the indicated days is shown.