[D-Ala2, D-Leu5]-Enkephalin or DADLE has been used for use in immunocomplex kinetic assay, to determine the activation of p70s6kby DADLE in the cell clones D2 and DOE and in non-transfected parental Rat-1 fibroblastsand to assess the analgesic effect of WIN55,212-2 in mice.