Inactivation of dok-3 gene locus. (A) Partial restriction maps of wild-type dok-3 locus, targeting construct, and inactivated locus after homologous recombination. Restriction enzymes used to define the loci are: B, BamHI and H, HindIII. The external probe used to screen HindIII-digested ES cells, which distinguishes the 15-kb wild-type and 5.3-kb targeted loci, is indicated. (B) Southern blot analysis of HindIII-digested wild-type and G418-resistant ES cell clones depicting the wild-type and inactivated dok-3 loci. (C) Western blot analysis of whole cell lysates obtained from wild-type and Dok-3^−/− mouse spleens. The blots were first probed with anti-Dok-3 antibodies and reprobed with anti-Dok-1 and anti-ERK2 antibodies to control for equal loading of whole cell lysates.