EYA3 and triple-negative breast carcinoma: As an effort to evaluate whether Eya3 affects PP2A-B55α’s substrate preference, we knocked down Eya3 and B55α in 66cl4 triple-negative breast cancer cells and performed phosphoproteomic analyses after TiO2 enrichment [which enriches pThr and pSer instead of pTyr phosphopeptides (49)], in order to identify changes in phosphosites in response to each KD condition (Fig. S5).