In vivo studies using a guinea pig model of infection suggest that mycolactone is responsible for both the extensive tissue damage and immunosuppression which accompanies Buruli ulcer.[1] The activity of mycolactone on cultured fibroblasts and macrophage cell lines produces a distinct cytopathic phenotype. The earliest effect is cell rounding, which occurs within 10 h after addition of mycolactone to cultured cells. At 36 h, treated cells are arrested in G1 of the cell cycle, and by 72 h, cells begin to die via apoptosis.[14]