MMP9 and Miyoshi myopathy: In particular, the dysregulation of the MAPK (Ras-Raf-MEK-ERK) and PI3K/AKT (PI3K/PTEN/AKT/mTOR) signaling pathways have been incriminated in the overexpression of MMPs, such as MMP-2 and MMP-9 [2] Also, alterations in RAC1B signaling pathway, with overexpression of FOXD1 (a neural crest associated gene), have been linked to MMPs up-regulation in MM.