PIP3-induced macropinocytosis is incompatible with chemotaxis. (A) Negative correlation of macropinocytosis and chemotaxis. The rate of macropinosome formation under different conditions was measured using FITC-dextran and fluorescence microscopy. Each data point represents a single cell that was imaged for at least 5 min. Data were taken from at least two independent experiments. Chemotaxis is represented qualitatively to avoid quantitative comparisons made under noncomparable conditions. (B) Deletion of PI 3-kinases from axenically growing cells restores chemotaxis to folate. (B, right) Insall chamber chemotaxis of axenic AX2 cells quintuply deleted for all p110 PI 3-kinases. (B, left) Chemotaxis of axenic wild-type cells (see data from Fig. 1 C for comparison).
