Cerebellar long-term depression (LTD) – which has been implicated in motor learning – is a form of synaptic plasticity in which transmission through synapses is decreased. LTD is induced when AMPA receptors are continuously removed from the post-synaptic membrane of Purkinje cells – but what are the cellular signals that cause the internalisation and degradation of these receptors? Cytosolic phospholipase A2α (cPLA2α), which produces arachidonic acid (AA), is thought to be important in LTD induction so, on page 3015, Tetsuya Hirabayashi and colleagues explore how this enzyme is activated in Purkinje cells. The authors show that cPLA2α translocates to the Golgi when AMPA receptors are stimulated, and that translocation is Ca²⁺-dependent. When LTD is chemically induced, they show, cPLA2α becomes phosphorylated and AA is released (the addition of pyrrophenone, a cPLA2α-specific inhibitor, abolishes AA production). The amount of GluR2 (an AMPA-receptor subunit) at the cell surface decreases persistently after the chemical induction of LTD; again, this effect is sensitive to pyrrophenone. The authors conclude that cPLA2α regulates the persistent decrease in surface expression of AMPA receptors; this underscores the role of cPLA2α and AA in cerebellar LTD.