Biochemical analysis of erythroid-specific KLF enhancers. (A) Potential TFBSs on KLF9-I. TF occupancies on the erythroid-specific KLF enhancer KLF9-I were annotated using Txn Factor ChIP track and ENCODE-motifs on the UCSC Genome Browser. (B) Result of EMSA analysis. Biotin-labeled oligos were incubated with nuclear protein extracts of K562, HeLa, or HEK293 cells in the presence or absence of unlabeled competing oligos. Shifted bands are indicated by arrowheads on the left. Band IV (red) was found to be erythroid specific and was only detected in K562 cells, but not in HeLa or HEK293 cells.