Inhibition of DDR1 prevents formation of polarized cysts in 3D. Inhibition of DDR1 prevents formation of polarized cysts in 3D. (A) Left and middle images: MDCK cells were grown in the 3D collagen gel in the presence of DMSO (control) or 1 μM DDR1-IN-1 for 7 d and subjected to indirect fluorescent imaging for F-actin (grey), GP135 (green), and laminin (red). Right images: cells were also were stained for acetylated tubulin (green) and GM130 (red). Arrows point to the lumen of cysts, whereas arrowheads point to basal staining of GP135 in the presence of DDR1-IN-1. (B) CaCO-2 cells were cultured in 2% Matrigel in the presence of DMSO (control) or DDR-IN-1 (1 μM) for 9 d. Left: cells were stained for ZO-1 (green) and f-actin (red). Right: cells were stained for GM130 (green) and f-actin (red). Representative images are shown. Pia Pernille Søgaard et al. LSA 2019;2:e201800276 © 2019 Søgaard et al.