IL-7 responsiveness of Tg mice. Staining for Bcl-2 is shown in wild-type (dashed line) and Tg thymocytes (filled line) upon 18 hours in vitro treatment with 3 ng/mL of recombinant murine IL-7 (right panels) or vehicle control (dimethyl sulfoxide [DMSO]; left panels) in gated DP cells. One representative experiment out of 4 is shown; all mice were young adults, age matched per individual experiment. Control antibody staining is shown only in the first histogram (dotted line).