Exposure of human peripheral blood monocytes to free arachidonic acid (AA) results in the rapid induction of lipid droplet (LD) formation by these cells. LD are formed by two different routes, namely (i) the direct entry of AA into triacylglycerol and (ii) activation of intracellular signaling leading to increased neutral lipid formation utilizing fatty acids coming from the de novo biosynthetic route. The latter predominates, accounting for 60‐70% of total LD formation, and can be completely inhibited by selective inhibition of the group IVA cytosolic phospholipase A2a, pointing out this enzyme as a key regulator of AA‐induced signaling. LD formation in AA‐treated monocytes can also be blocked by the combined inhibition of the mitogen‐activated protein kinase family member p38 and JNK, which correlates with inhibition of cPLA2a activation by phosphorylation. Since cPLA2a has no effect on neutral lipid formation there must be a step in the mechanism of LD biogenesis that is critically dependent on the enzyme, e.g. generation of a positive curvature at the organelle baseline.Supported by Grant SAF2013‐48201‐R from the Spanish Ministry of Economy and Competitivenes