beta2m<null> beta2MKO beta2m<tm1Unc> beta2m<0> B2m<tm1Unc> beta2m<o> targeted mutation 1, University of North Carolina b2m<null> http://identifiers.org/mgd/MGI:1857133 beta2-m-KO MHC-I<-> beta2M- Null/knockout MGI:1857133 I<0>