The pCiB-yin plasmid contains a recombination-mediated cassette exchange (RMCE) cassette that consists of two inverted attB sites surrounding a y+mDint marker. In the presence of phiC31:int integrase, the attB cassette can undergo RMCE with a target in the genome that contains inverted attP sites, replacing the target attP cassette with the y+mDint marker.