A targeting vector containing the COP4/EYFP, a modified channel rhodopsin-2 gene from Chlamydomonas reinhardtii (ChR2(H134R), and enhanced yellow fluorescent protein fusion gene, and the a self-excising PGK-neo cassette, ACNF, was used to disrupt the targeted gene. The neo cassette removed itself. (J:175440, J:177023)