Western blot of rat testes lysate showing specific immunolabeling of the ~46 kDa EphrinB phosphorylated at Tyr331 (Lane 1). The phosphospecificty of this labeling is shown in Lane 2 (lambda-phosphatase). The blot is identical to the control except that it was incubated in lambda-phosphatase (1200 units for 30 min) before being exposed to the Anti-Tyr331 EphrinB. The immunolabeling of the EphrinB is completely eliminated by treatment with lambda-phosphatase.