UASp sequences regulate expression of the Spc105R B isoform, in which the RISF motif in the N-terminal region has been mutated to RIAF (non-phosphorylatable mutation). The coding sequence is tagged at the C-terminal end with 6xTag:MYC. Silent mutations have been introduced to render the transgene resistant to RNAi mediated by the P{TRiP.GL00392} transgene.