(A) Protocol used to generate EBHX cell lines. (B) Immunodetection of HOX11 protein (37 kD, arrow) in EBHX cell lines by immunoprecipitation of radiolabeled proteins with HOX11-specific antiserum. PGMD1, an IL-3–dependent myeloid progenitor line used as negative control; HX3, a bone marrow-derived HOX11-immortalized line used as positive control; EBHX, day 6 EBs generated from MSCV-HOX11 transduced ES cells; EBHX1, EBHX4, EBHX11, three EB-derived HOX11-immortalized cell lines. (C) Northern blot analysis with a neo probe demonstrating LTR-directed (4.0 kb) HOX11 mRNA (which contains downstream neo sequences) and pgk-directed (1.3 kb) neo mRNA in EBHX cell lines. CCE ES, wild-type ES cells; ES/HOX11, MSCV-HOX11 transduced ES cells; 3T3/HOX11, NIH3T3 fibroblasts transduced with the MSCV-HOX11 vector.