HMOX-1 KO design. A 7-kb mouse genomic sequence of the mouse Hmox-1 gene, from the start codon ATG to the stop codon, was deleted on mouse chromosome 8 C1, between coordinates chr8 75093750 and 75100019. The deletion was performed in ES cells with humanized M-CSF, SIRPα, CD47, and deletion of mouse Rag2 and IL-2Rγ genes. The mouse embryo comprising the donor ES cells was incubated in vitro and then implanted into a surrogate mother to produce an F0 mouse fully derived from the donor ES cells. Mice with Hmox-1 gene deleted were identified by genotyping using the MOA assay described above. Mice heterozygous for deletion of the Hmox-1 gene were bred to homozygosity for all genes. EP, electroporation; KO, knockout.