Detection of Emp isoforms in macrophage membranes. Macrophage membrane proteins were separated by 18% SDS-PAGE and transferred to a nitrocellulose (NC) membrane. The NC membrane was probed with anti-Emp antibodies (lane 1) and immunoreactive bands were detected with an enhanced chemiluminescence system, or the NC membrane was incubated with radioiodinated erythroblasts (lane 2) and processed for autoradiography. Molecular weight standards are shown on the left.