saturation experiments were performed in the absence or in the presence of morphiceptin ( 1 microm ) , which masks the mu sites , d-ser2-leu-enkephalin-thr6 ( 100 nm ) , which masks delta sites , or dadle ( 5 microm ) , which was found to mask the delta , mu , and benzomorphan receptor .
C0014294
leu-enkephalin
C0079286
dadle