Ank-1^1674/1674 are null mutants exhibiting severe RBC membrane abnormalities. (A) Quantitative RT-PCR measurement of Ank-1 mRNA levels in 6-week-old wild-type (wt), Ank-1^1674/+, and Ank-1^1674/1674 mice. Error bars represent SD. Student t test P values between wt and Ank-1^1674/1674 were significant (P < .05) and not significant (P > .05) between wt and Ank-1^1674/+. (B) Coomassie blue–stained SDS polyacrylamide gradient gel (4%-20%), and (C) 5% SDS polyacrylamide gel of membrane ghosts from wt, Ank-1^1674/+, and Ank-1^1674/1674 mice. (D) Immunoblot of transmembrane proteins in red cells of wt, Ank-1^1674/+, and Ank-1^1674/1674 mice probed with anti–Ank-1 and anti-actin antibodies. (E) Immunostaining of adult bone marrow cytospins from wt, Ank-1^1674/1674 mice with anti–ANK-1 antibodies, and an IgG control. (F) Immunoblot of transmembrane proteins in red cells of wt, Ank-1^1674/+, and Ank-1^1674/1674 mice probed with antibodies against the indicated proteins. (G) Freeze-fracture EM images of red cell membrane skeletons from wt, Ank-1^1674/+, and Ank-1^1674/1674 mice. JC indicates junctional complexes; Sp, spectrin tetramers; and Ank, ankyrin.