Retroviral integration at the MDS1/EVI1 locus. (A) Location of the 14 independent RISs identified within the Mds1/Evi1 locus. Black arrows indicate RISs with the provirus in the same orientation as transcription; gray arrows indicate RISs with the provirus in the reverse orientation. Locations mapped using July 2003 human genome assembly. (B) RIS-specific PCR using insert-specific 5′ genomic nested forward (F) primers and 3′ LTR-R primers to confirm the presence of the fusion sequence in blood granulocytes from individual animals, shown for insertion nos. 1, 2, 3, 5, and 9 (see Table 1 for list of inserts and Table S1 for primer sequences). MPT indicates months after transplantation. Expected amplification product size is indicated. (C) Taqman PCR measuring the contributions from individual Mds1 clones over time. Animal RC501 underwent transplantation in June 1998. The top panel shows the level of insert no. 1 in granulocytes. The bottom panel shows the level of insert no. 2 in granulocytes and mononuclear cells. A total of 4 additional inserts analyzed by Taqman showed similar results, with no significant change in the level of contribution of the MDS1 RIS over time in granulocytes or mononuclear cells (MNCs).