The Pim2–PML-RARα–induced leukemia is transplantable. (A) GFP-positive cells were detected by flow cytometry in the bone marrow and spleen from secondary and tertiary recipients of Pim2–PML-RARα (Pim2-PRα) cells. (B) Photographic image of spleens of the indicated mice. (C) Histologic section of the spleen from secondary and tertiary recipients, stained with hematoxylin and eosin (original magnification ×100). The arrows indicate the infiltration of the spleen of secondary and tertiary recipients by myeloid cells. (D) Southern blot analyses of provirus integration into the bone marrow of primary (lanes 1-4) and secondary (lanes 5-6) transplants. BM cells from lane 1 were used for secondary transplantation. The genomic DNA was digested with HindIII and SacI and probed with GFP sequences. To monitor for loading in the HindIII digest, the blot was reprobed with cyclinD1. (E-F) Real-time RT-PCR was performed on the mRNA samples isolated from spleen of recipient mice. Gapdh was used as an internal control for each experiment. Expression was analyzed in several mice from each group and was repeated independently 2 times. Data shown here are from 1 representative mouse from each group of animals that underwent serial transplantation.