MMP9 and osteosarcoma: Interestingly, signaling via MEK/ERK has been shown to increase MMP-9 production in a range of cancer types, including SCC [51], chondrosarcoma [52], breast cancer [53], fibrosarcoma [54], prostate cancer [55], osteosarcoma [56], and glioma [57], raising the possibility that MEK/ERK-mediated APA plays a role in controlling MMP-9 expression in different types of tumors, possibly in response to different stimuli.