Working model for the ordered events in FA turnover and the role of APC-mediated actin assembly. FA assembly (top panels) is similar in APC-WT and APC-m4 cells, with FAs growing for an average of 4.8 min before reaching peak maturity (maximum size). During this phase, microtubule plus ends are repeatedly captured at FAs and then retract, but rarely does this result in delivery of an autophagosome to the FA. However, FA disassembly (the time from peak maturity to complete disappearance) is strikingly different in APC-WT versus APC-m4 cells (bottom panels), taking approximately sevenfold longer in APC-m4 cells (17.5 versus 2.5 min). In APC-m4 cells, microtubule capture events are approximately three times longer than in APC-WT cells (76 versus 26 s), and autophagosome dwell times at FAs are approximately twice as long (72 versus 36 s). However, the frequency of microtubule visits is reduced in APC-m4 cells, as the average time between microtubule visits is increased. In APC-WT cells, once the FA reaches full maturity (stops growing), the next microtubule capture event typically results in autophagosome delivery, leading to rapid disassembly of the FA. However, in APC-m4 cells, microtubule capture and autophagosome delivery occur repeatedly at mature FAs as they slowly disassemble. Zooms in lower panels depict the spatial organization of F-actin and FA components. In APC-m4 cells, F-actin levels and organization are reduced, and the density of FA components is reduced (see zooms in lower panels). Black arrows on the left sides of panels indicate normal timing of events in FA assembly and disassembly, while red arrows indicate prolonged events in FA disassembly in APC-m4 cells. The large red arrow on the right indicates an increase in the number of times specific steps in FA turnover are repeated in APC-m4 cells. MT, microtubule; PM, plasma membrane; SF, stress fiber.