The insertion P{EP}CTCFGE22007 is found 15bp downstream of the transcription start site for CTCF.
CTCFGE22007 homozygotes appear as wild-type, although F[[2]] embryos die at various stages frm secondary mutations (~5/200 survivors).
CTCFGE22007/Df(3L)0463 trans-heterozygotes appear as wild-type.