FYN and breast carcinoma: In MDA-MB-231 breast cancer cells, fyn kinase was shown to co-localize with the β1 subunit of VGSC, and pharmacological, as well as siRNA-mediated fyn inhibition, resulted in inhibition of the β1-mediated process outgrowth (which is proposed to be mediated through ERK1/2 phosphorylation) (21).