MMP2 and head and neck squamous cell carcinoma: However, the cloned IL-33-overexpressing HNSCC cells together with the autocrine cancer-secreting function increased MMP2 and MMP9 expression spontaneously and, conversely, the blockade of the IL-33 expression enhanced the attenuation of MMP2 and MMP9, suggesting that IL-33 was an upstream mediator of the signaling cascade.