Imprecise excision in a line containing both the P{EP}EP3668 insertion (located 5' of Best1) and P{EP}31-1 (located 3' of Best1) has resulted in a deletion of the sequence between the two insertions (removing the entire Best1) locus which leaving genomic DNA flanking the outside of the two insertions intact.
Homozygotes have no gross morphological abnormalities and have a normal lifespan.