HIF-1α, although induced by hypoxia, has also been shown to induce hypoxic TB granulomas (87), to inhibit apoptosis of Mtb-infected foamy macrophages (impairing killing of intracellular Mtb) (154), and induce MMP-1 (a collagenase that may cause tissue destruction) (218). Here, MMP1 is linked to tuberculosis.