An FRT cassette containing a transcription stop signal and a y+t* marker separates a αTub84B promoter from a mutated hpo coding region that carries mutations in 4 of the 5 autophosphorylation sites of the linker region (T356A, T374A, T387A, T421A). The 5th autophosphorylation site T431 has not been mutated (this residue is also part of a mats protein binding site in the wild-type protein).