Figure 2.

RAS-RAF pathway in relation to miR-31 and RASA1. When a growth factor ligand binds to epidermal growth factor receptor (EGFR), phosphorylation of the protein tyrosine kinase results in the recruitment of Grb2 adaptor protein and son of sevenless (SOS). This phosphorylation activates the RAS protein, which consequently bind to Raf kinase. Phosphorylated RAF in turn phosphorylates and activates subsequent downstream proteins MEK1/2 and ERK1/2, which result in nuclear transcription of genes responsible for cell proliferation. miR-31 directly inhibits RAS p21 GTPase Activating protein (RASA1) which affects the GTPase activity of RAS.