Overexpression of Bcl-2 in hematopoietic tissues of Sca-1 Bcl-2 transgenic mice. (A) Transgene construct. An 865-bp murine Bcl-2 cDNA fragment was inserted into exon one of a 14-kb Sca-1 (Ly-6E) expression cassette. H indicates HindIII. (B) Transgene copy number determination. A Southern blot containing HindIII-digested DNA was probed with a Bcl-2 fragment to reveal the 1.4-kb endogenous gene and 4.7-kb transgene. Ln 479 contains 20 and Ln 2 contains 7 copies of the transgene. (C) Northern blot analysis for Bcl-2 transgene expression in several adult tissues. Bcl-2 is expressed in liver and kidney in Ln 479 and Ln 2 Bcl-2 transgenic (tg) animals. (D) Western blot analysis of Bcl-2 protein expression in Ln 2 and Ln 479 transgenic animals. Bcl-2 is overexpressed in several transgenic tissues, including kidney, thymus, spleen, and bone marrow, as compared with nontransgenic (wild-type [wt]) littermates. In general, no obvious abnormalities were found in the transgenic adults. Blood smears showed no morphologic differences or leukemic cells, and hematocrits did not differ between the transgenic and nontransgenic adults (data not shown).