Moreover, under hypoxic conditions, interstitial collagenases, such as MMP−1 that is able to degrade extracellular fibrillar collagen, generates not only a compliant environment that allows drug delivery but also provides metastatic tumor cells the ability to extravasate from the primary tumor tissue into the blood and lymph to colonize distant metastatic sites [58]. This evidence concerns the gene MMP1 and neoplasm.