Insertion 24bp downstream of the Mcr transcription start site.
The luminal chitin fibrils within the tracheal system appear disorganised in stage 15 mutant embryos.
Mutant embryos lack nearly all ventral denticle belts and have ectopic deposits in the region of the salivary glands.
Mutant embryos show defects in septate junction structure in the salivary glands, hindgut and trachea (assayed by cora protein localisation).
Excision of the insertion can revert the lethal phenotype.