Secondary transplantation demonstrates sustained, increased levels of F cells, HbF, and Hb. (A) The percentages of F cells in control, untreated, and treated V5-MSCV-MGMT animal groups (as indicated), both at baseline (1° Before) and after (1° After) drug treatment are shown. Also shown are the values in secondary transplantation recipients (2°) of BM from control, untreated, and drug-treated animals. The levels of F cells in the mice after treatment and in secondary recipients derived from them were statistically different from the baseline values before treatment as determined by the Student t test. P values are shown for each, compared with the baseline value. (B) The Hb levels in 1° and 2° control (untreated) and treated animal groups (as indicated) are shown. Also shown is the mean Hb level in animals transplanted with mock-transduced cells. Data represent the mean plus or minus SEM. (C) Top panel: cellulose acetate gel electrophoresis of RBC lysates from a drug-treated, V5-EF1-MGMT animal before (Pre) and after (Post) BG/BCNU administration and from 2° transplantation recipients derived from this primary mouse. The samples of the first 2 control lanes and the 2° transplantation lanes were run on one gel as indicated by the vertical lines. Pre and post samples in the 1° transplantation lanes were run on different gels at different times because samples could not be preserved intact for 20 weeks. Bottom panel: Hb levels of the primary animal before (Pre) and after (Post) drug treatment and of 2° transplantation recipients derived from the primary animal.