Blebs rapidly re-orientate in cells chasing a micropipette releasing cyclic-AMP. (A) Illustration of re-orientation experiment: a cell is attracted toward a needle releasing cyclic-AMP until it becomes elongated, then the needle is moved to the flank, inducing a turn. This cell follows the stereotypic pathway by first producing F-actin microspikes facing the needle (12 s), then a bleb (19 s; dot), and finally a pseudopod (32 s). (B) Examples of blebs produced during chemotactic re-orientation (see Video 7 for a selection of turning events). (C) Timing of events during re-orientation; mean and range are shown. (D) Illustration of the stereotypic sequence of events when a cell re-orientates through a new projection on its flank. Microspikes are apparent after 8 s, then at 9 s a bleb forms (single yellow arrow) and together with a second bleb, transforms into a pseudopod (double yellow arrows). (E) Behavior of 30 individual cells during re-orientation. This represents the same set of cells as in C. Only turns where the cells produce a new leading edge from their flank were analyzed. Ax2 cells were starved for ∼5.5 h and express ABD-GFP, except for the cells used for PIP3 accumulation in C, which expressed CRAC-PH-GFP. Bar, 10 μm.