Exon 6 was removed via cre-mediated recombination. This exon encodes the heme-binding domain. RT-PCR confirmed the loss of exon 6 in mutants, demonstrating presence of some mRNA containing exon 2, but none containing exon 6. Immunohistochemistry failed to detect any staining in the cytoplasm, neurites, varicosities, cortex or striatum of mutants. (J:106816)