A sequence cassette has been introduced into the attP site present in TI{TI}mthl2attP, restoring the deleted mthl2 sequence and tagging it with Tag:V5. The tag is followed by a 2A-lexA::p65 cassette, resulting in the lexA::p65 driver being expressed as a separate protein under the control of the endogenous mthl2 regulatory sequences. A single loxP site is present downstream of the driver sequence (markers present in the progenitor insertion and donor plasmid have been removed using P1cre).