Notably, 15/7 epitope expression is most readily induced on ??4??1, as compared with other ??1 integrins (Bazzoni, G., L. Ma, M.L. Blue, and M.E. Hemler, manuscript submitted for publication), and thus is an especially useful tool for evaluating altered ??4??1 conformations.Negligible 15/7 epitope expression was seen for ??4wt and mutant ??4 integrins in K562 cells in the absence of stimulation (T