Sequence has been inserted into the attP site in TI{TI}dallyKO, reconstituting a mutated dally locus in which the C-terminal sequence that encodes the glycosylphosphatidylinositol (GPI) attachment sites has been replaced by sequence encoding a CD2 transmembrane domain. In addition, a YFP tag has been inserted internally, near the N-terminal end of the coding sequence (the tag is inserted downstream of the signal peptide sequence).