A method for regulating Src and its downstream signaling pathway which includes binding between Src and Na+/K+-ATPase is disclosed. The Na+/K+-ATPase/Src complex is a functional receptor for cardiotonic steroids such as ouabain. Also disclosed are Src inhibitors or activators which include either Na+/K+-ATPase or Src that interfere with the interaction between the Na/K-ATPase and Src, act via a different mechanism from ATP analogues, and is pathway (Na+/K+-ATPase) specific.