Expression of nub^hs.PC at 2.5 to 3 hours of development, using heat shock, results in increased lethality compared to control flies, with 51% of the embryos carrying nub^hs.PC failing to hatch. 63% of these unhatched embryos show a gap gene-like cuticle defect; the first two abdominal segments are deleted, and the second and third thoracic segments may be fused or missing. Head involution does not occur and the head is deformed, with a misshapen head skeleton, although the mouth hooks form normally. 22% of embryos carrying nub^hs.PC and derived from homozygous mothers produce 2-3 abdominal denticle belts when heat shocked at 1.75 to 2.75 hours of development.