The D7 monoclonal antibody (mAb) reacts with Ly-6A. 2 and Ly-6E.1, members of the Ly-6 multigene family. Ly-6A⁄E molecules are expressed on multipotent hematopoietic stem cells, activated T cells, and peripheral B cells on mice that express the Ly-6.2 haplotype. The D7 mAb can be used in immunostaining for flow cytometry, Western Blot, and immunoprecipitation.