I found that Sec23j13C8 is not lethal in combination with Sec239G (an amorphic EMS allele of Sec23) or with Df(3R)ED5187 (a deficiency that deletes Sec23). In other words, the Sec23j13C8 fly line complemented these Sec23 mutation and deficiency lines. This suggests the lethality of the Sec23j13C8 allele does not come from disrupting Sec23 function.