The Lyl1 promoter proximal region contains 2 evolutionarily conserved core promoters. (A) Lyl1 is expressed in endothelial (MS1), hematopoietic progenitor (416B), and megakaryocytic L8057 cell lines but not in a T-cell line (BW5147). Total cDNAs were subjected to real-time PCR analysis. The level of Lyl1 in RNA prepared from whole E11.5 mouse embryos, normalized by the level of actin, was assigned a value of 1. The relative abundance of Lyl1, normalized by the level of actin, is depicted by black bars ± SD. (B) Nucleotide sequence alignment of the Lyl1 proximal promoter region (species as described in Figure 1). Conserved Ets binding sites (EBS), GATA binding sites (GBS), and the GGCC motif as well as the 2 transcriptional start sites (curved arrows) are indicated. The arrowhead designates the cloning site used to separate the 2 core promoters Lyl1P1 and Lyl1P2. (C) The Lyl1 proximal promoter contains 2 core promoters. Shown on the left are the reporter constructs in which either the entire Lyl1P proximal promoter region or the 2 core promoters Lyl1P1 and Lyl1P2 were inserted upstream of the luciferase gene in the promoterless pGL2B vector. Following from left to right are the results of transient transfection assays in MS1, 416B, and L8057 showing luciferase activities corrected for transfection efficiency with the pEF-BOS LacZ plasmid. The luciferase activities are presented as fold increase over the activity of the control (pGL2B) vector, which was assigned a value of 1. Each bar represents the mean relative luciferase activity from at least 2 experiments performed in triplicate ± SD.