Fumonisin B1 is a mycotoxin produced from F. moniliforme, a prevalent fungus of corn and other grains. Outbreaks of food poisoning in livestock and humans following the consumption of Fusarium infested corn are caused by fumonisins. It functions as an inhibitor of ceramide synthase (sphingosine N-acyltransferase). Fumonisin B1 attenuates the response of P388D1 cells to PAF and LPS by inhibiting ceramide formation. It also blocks the apoptotic response of HaCaT cells to the antiproliferative drug hexadecylphosphocholine, again through inhibition of ceramide production. Incubation of Swiss 3T3 cells with fumonisin B1 results in both an altered cell morphology due to disruption of axonal growth and a decrease in cell proliferation.