C57BL/6-C3<sup>−/−</sup> (G6 backcross) from Dr. Rick Wetsel (University of Texas Health Sciences Center at Houston) were further backcrossed in-house. In the C3 gene: "A genomic fragment containing 2.3 kb of the 5' flanking region and the first 105 bp of exon 1 was replaced with a neomycin selection cassette."
This strain is cryo-preserved.