Mediates the deactivation of rap1 and plays an important role in spatially and temporally regulating cell adhesion and chemotaxis by controlling attachment disassembly in the leading edge through the regulation of myosin II assembly and disassembly. Overexpression leads to defective chemotaxis. Translocates to the cell cortex in response to chemoattractant stimulation and localizes to the leading edge of chemotaxing cells via an F-actin-dependent pathway. Cortical localization is negatively regulated by ctx. Expressed at all stages of development. Null cells show defects in spatial regulation of the cell attachment at the leading edge. They also have extended chemoattractant-mediated rap1 activation kinetics and decreased myosin II assembly.