Expression of mistargeted syntaxin 4 prevents cyst-formation in 3D MDCK culture.

<p>(<b>A</b>) MDCK cells stably expressing Syn4-Δ29 were cultured in 3D collagen. Syntaxin expression was induced with DOX two days after seeding, and culture was continued for an additional 6 days. Cells were fixed and immunostained for GP135 protein, an apical marker, Syn4-Δ29 (myc) and nuclei. Two different panels are shown for cells that express Syn4-Δ29 after induction to represent the variety of defective cysts found in the cultures. (<b>B</b>) Quantitation of cyst formation. Cysts consisting of polarized cells or disorganized “non-cysts” consisting of nonpolarized cells (as shown in A) were counted and are expressed as percentage of total structures.