Tyrosine-protein phosphatase non-receptor type 5 (STEP) is involves to regulate AMPAR trafficking and negatively regulates AMPAR surface expression thereby contributing to mGluR-LTD. STEP promotes LTD by stimulating synaptic weakening by dephosphorylation of ERK1/2 and subunits of NDMA and AMPA receptors. STEP has been shown to promote NMDA internalization.