Production and validation of GATA1 isoform specific expression vectors. (a) production of GATA1s and GATA1FL transcripts from wild type (WT) HEK293 cDNA black arrows represent the position of the GATA1WT/FL primers, white arrows mark GATA1s primers. (b) Map of the pEF6 GATA1-IRESGFP expression plasmid. (c) Western blot of GATA1 protein expression from GATA1FL (lane 1) and GATA1s (lane 2) plasmids respectively, using Santa Cruz GATA1 M20 antibody. Arrows show the position of the 40 and 50 kDa size markers, the expected protein sizes are 47 kDa GATA1FL and 40 kDa GATA1s, a loading control is also shown. (d) Luciferase assay using a GATA1 reporter plasmid showing fold induction of luminescence with expression of the WT GATA1 plasmid versus the mutated GATA1FL plasmid (84 Met-Thr).