Prior to migration, during a process known as epithelial-mesenchymal transition, there is a loss of cell contact, remodelling of the [[cytoskeleton]] and increased motility and interaction with extracellular components in the matrix.<ref name= "pmid8714286" >{{cite journal |vauthors= Hay ED| title = An overview of epithelio-mesenchymal trans-formation | journal = ActaanatomicaActa Anatomica | volume = 154 | issue = 1 | pages = 8–20| date = 1995 | pmid = 8714286 | doi=10.1159/000147748}}</ref> An important step in this process is the suppression of adhesion protein [[E-cadherin]] present on [[epithelial cells]] to initiate the migration process. This suppression mechanism occurs via the [[growth factor]] BMP signalling to turn on a transcriptional repressor Smad-interacting protein 1 (Sip1) and marks the beginning of the epithelial-mesenchymal transition.<ref name= "pmid11430829" >{{cite journal |vauthors= Comijn J, Berx G, Vermassen P, Verschueren K, van Grunsven L, Bruyneel E, Mareel M, Huylebroeck D, van Roy F| title = The two-handed E box binding zinc finger protein SIP1 downregulates E-cadherin and induces invasion | journal = Molecular Cell| volume = 7 | issue = 6| pages = 1267–1278| date = 2007| pmid = 11430829 | doi = 10.1016/S1097-2765(01)00260-X }}</ref>
