The pCMV-ProLabel® and pCMV-ProLink™ mammalian cloning vectors are intended for mammalian cell expression of a GPCR or other protein of interest as a fusion protein with an ED [ProLabel (PL) or ProLink (PK)] tag. The resulting ED-tagged protein, upon interacting with an EA-tagged protein (most typically co-expressed in a EA-parental cell line), gives rise to EFC.