Phosphatidylinositol 4 kinases catalyze the phosphorylation of phosphatidylinositol (PI) or specific mono phosphate derivatives of PI at position 4 on the inositol ring to generate PI4P, PI(3,4)P[[2]] or PI(4,5)P[[2]]. The resulting phosphoinositides can then act as signalling molecules to mediate/regulate a range of cellular and physiological processes, including cell polarity, cell migration, autophagy, growth, development, and ageing. (Adapted from FBrf0227909.)