Sequence has been inserted into the attP site in TI{TI}MadattP.KO, reconstituting a Mad locus in which both the Mad-PA and Mad-PB isoforms are tagged with 3xTag:HA. The 3xTag:HA sequence is inserted so that it tags the N-terminal end of the Mad-PA isoform, and is internal (at codon 71) in the Mad-PB isoform.