HMOX1 and monocytic leukemia: Dorresteijn et al. (2015) have recently shown that LPS stimulation selectively downregulates HO-1 expression in PBMCs, monocytes, granulocytes, macrophages, and DCs from healthy male donors via stimulating Bach1, which transcriptionally represses HO-1 expression. However, similar LPS stimulation results in upregulation of HO-1 expression in mouse lung macrophages and human monocytic leukemia cell lines (Dorresteijn et al., 2015).