Insulin stimulates glucose transport largely by mediating translocation of the insulin-
sensitive glucose transporter (GLUT4) from an intracellular compartment to the plasma
membrane. Using single cell microinjection of 3T3-L1 adipocytes, coupled with
immunofluorescence detection of GLUT4 proteins, we have determined that inhibition of
endogenous p21 ras or injection of oncogenic p21 ras has no effect on insulin-stimulated
GLUT4 translocation. On the other hand, microinjection of anti-phosphotyrosine antibodies …