MAPK3 and ductal breast carcinoma in situ: Moreover, the knockdown of FOXQ1 in ERK1 knockout DCIS-iFGFR1 cells abolished the AP20187-stimulated cell proliferation, and PD032901 equally inhibited ERK1 knockout DCIS-iFGFR1 cells with FOXQ1 knockdown in either absence or presence of AP20187 treatment (Fig.