U2AF2 and metastatic neoplasm: Importantly, the U2AF2 E2/E3 ratio was also higher in the metastatic tumors, while the IIIb/IIIc FGFR2 transcript ratio was reduced (Supplementary Fig. 12l), in agreement with our earlier observations, showing that IWS1 phosphorylation promotes FGFR2 exon 8 skipping22.