UAS regulatory sequences drive expression of a human codon-optimized Cas9 endonuclease. The Cas9 sequence is the same used previously in the M{Act5C-Cas9.P} and M{nos-Cas9.P} constructs. The advantage of this construct over P{UAS-Cas9.P} is that Cas9 is expressed at a lower level and causes less toxicity. It also shows less leaky expression in the absence of a GAL4 driver.
