Schematic diagram of the four main types of cell polarity.
Yellow and blue are putative polarity proteins shown in the polarised localisation required for them to control cellular orientation. (A) Asymmetric cell division of a stem cell. (B) Front-rear cell polarity of a migrating fibroblast. (C) Apical-basal cell polarity of epithelial cells (D) Planar cell polarity of epithelial cells in a top view.