Sec23 or Sec24CD null heterozygotes partially rescue cactin-RNAi delamination defects. (A) Normalized expression of Sec23, Sec24CD, gkt, and tws (for all isoforms). (B) Normalized expression of Sec23-RD and Sec24CD-RA (isoforms highly expressed in cactin-RNAi compared to control). In each case, the mean expression level in the control is set to one and the expression level in cactin-RNAi is normalized to the mean of the control. (C) Proportion of mRNA levels of Sec23-RD and Sec24CD-RA isoforms in all isoforms. (D) Quantification of delamination defects in stage 10 egg chambers. (E) Images of border cell clusters of c306-Gal4 driven UAS-cactin-RNAi together with control (cross to w1118), gkt-RNAi, Sec23 null mutant heterozygote, Sec24CD null mutant heterozygote, and tws null mutant heterozygote. Yellow arrowheads indicate the apical junctions in the border cell clusters. Scale bars, 20 μm. (F and G) Schematic of working models showing how Cactin regulates aPKC and Crb apical localizations. (F) Model showing expression and trafficking of Crb and aPKC in control cells. (G) Model showing accumulation of excess apical Crb and aPKC in a Cactin knockdown border cell. (H and I) Schematic drawing showing how Cactin knockdown disturbs border cell organization and delamination. (H) Control border cell cluster. (I) Cactin knockdown border cell cluster.