TEF produces the highest transcriptional activation through the LMO2 PAR-binding site. (A) Increasing amounts of FLAG-tagged PAR expression constructs were cotransfected into K562 cells with the TATA-PAR reporter construct. The level of TATA-PAR luciferase expression in the absence of PAR proteins was set as 1. A Western blot analysis was also performed to ensure approximately equal expression of the factors from each construct. (B) Endogenous coexpression of LMO2 and the PAR genes in primary erythroid cells was demonstrated by RT-PCR analysis of RNA from human reticulocytes. The 2 control lanes were from reactions incubated with the DBP primers; similar negative results were obtained with the other primer sets.