Df(1)BSC877 was isolated as a FLP recombinase-induced recombination event involving PBac{WH}f04451b and P{XP}norpAd05473. The deletion was isolated as a chromosome carrying two copies of the miniwhite marker in progeny of PBac{WH}f04451b/P{XP}norpAd05473; MKRS, P{hsFLP}86E/+ females crossed to FM7h/Dp(2;Y)G, P{hs-hid}Y males. These females were heat shocked as larvae as described in Parks et al., Nature Genetics 36: 288-292, 2004 (FBrf0175003). This cross and crosses in preceding and succeeding generations maintained the original genetic background of the Exelixis insertion stocks (Thibault et al., Nature Genetics 36: 283-287, 2004; FBrf0175002). The recombination event generated the genetic element P+PBac{XP3.WH3}BSC877 from the segment of PBac{WH}f04451b to the left of its FRT site and the segment of P{XP}norpAd05473 to the right of its FRT site. The breakpoints of Df(1)BSC877 predicted from the Release 5 genomic coordinates of the transposable element insertion sites are  X:3822414 ;4218814..4218913 and the cytological breakpoints predicted from these coordinates are 3F7;4B6. It failed to complement brnfs.107.