FRS2 and breast cancer: When downstream signalling changes that occur in basal B tumourspheres upon MET and FGFR inhibition were interrogated, co-inhibition of MET and FGFR signalling abrogated tyrosine phosphorylation of FRS2, resulting in loss of ERK1/2 activation (Supplementary Fig. 4c) consistent with our observations in murine claudin-low-like breast cancer.