FGFR1 and ductal breast carcinoma in situ: To assess the specific role of ERK1 or ERK2 activation in FGFR1 signaling-promoted FOXQ1 expression, we treated ERK1 knockout or ERK2 knockout DCIS-iFGFR1 cells generated previously 15 with vehicle or AP20187 and assayed FOXQ1 expression.