UAS regulatory sequences drive expression of a coding sequence that consists of an HSV epitope tag, a TimeSTAMPt cassette, a Tag:HA tag and CaMKII. The CaMKII protein is constitutively tagged with Tag:HA, but the presence of the TimeSTAMPt cassette means that tagging of CaMKII with the HSV epitope tag is drug-dependent, requiring the presence of a specific inhibitor (BILN-2061). In the absence of BILN-2061, the TimeSTAMPt cassette catalyzes its own cleavage from the protein sequence, and thus the upstream HSV epitope tag is removed from the CaMKII protein. In the presence of BILN-2061 this cleavage is inhibited, and thus any CaMKII protein newly synthesized in the presence of the inhibitor is tagged with the HSV epitope tag in addition to Tag:HA.