Activation of the distal and proximal LMO2 promoters by the LTR. (A) The origin of the 2 transcripts from human LMO2, both of which encode the same protein, is indicated along with the relative distances of the retroviral insertion site from the 2 transcriptional start sites. The relative LMO2 expression from the 2 promoters was established in several clones using TaqMan Gene Expression Assays. The location of each primer pair is indicated on the diagram. Results are expressed as the percentage of the K562 cell control. (B) Northern blot analysis of RNA from 2 clones having an LTR-GFP insertion (G-22 and G-25) and positive control (K562) and negative control (Jurkat) cells was performed. The transcript from the proximal promoter was more abundant that that from the distal promoter in both clones, consistent with the results obtained with the qRT-PCR analysis in panel A.