Fig 1: Regulation of EPX by HMX2 and HMX3.(A) Quantification of EPX expression in primary granulocytes (neutrophils, eosinophils, basophils) and selected cell lines by RQ-PCR. (B) SiRNA-mediated knockdown of HMX2 (left) and HMX3 (right) resulted in elevated expression levels of EPX. Reduced expression of HMX2 and HMX3 and elevated expression of EPX was also shown by Western blot analysis. Asterisks indicate calculated p-values obtained by t-Test analysis of controls (siCTR) and siRNA-targeted knockdown. (C) Forced expression of HMX2 in HL-60 cells resulted in reduced expression level of EPX (left). SiRNA-mediated knockdown of EPX resulted in activation of CD11B expression (right). (D) A genomic map of the locus for EPX was obtained from the UCSC genome browser, showing potential transcription factor binding sites including one for HMX1. (E) Reporter-gene assay in NIH-3T3 cells using a fragment containing the identified HMX-site. Forced expression of HMX2 resulted in decreased reporter-gene activity, demonstrating a direct repressive impact. (F) Forced expression of EPX in EOL-1 slightly reduced the expression level of CD11B. Microscopical inspection of Giemsa-May-Grünwald-stained EOL-1 cells indicated strongly induced apoptosis by forced EPX expression as possible consequence of continued differentiation. Living cells resemble differentiated cells after DMSO-induction.