sentences:  Eph receptors in turn are classified as either EphAs or EphBs based on their binding affinity for either the ephrin-A or ephrin-B ligands.Of the eight ephrins that have been identified in humans there are five known ephrin-A ligands (ephrin-A1-5) that interact with nine EphAs (EphA1-8 and EphA10) and three ephrin-B ligands (ephrin-B1-3) that interact with five EphBs (EphB1-4 and EphB6).Ephs of a particular subclass demonstrate an ability to bind with high affinity to all ephrins of the corresponding subclass, but in general have little to no cross-binding to ephrins of the opposing subclass.