However, in ERK2 knockout DCIS-iFGFR1 cells, activation of FGFR1 signaling was unable to increase c-FOS and FOXQ1 protein expression, and T-5224 did not show any significant effect on c-FOS and FOXQ1 protein expression in ERK2 knockout cells (Fig. Here, FGFR1 is linked to ductal breast carcinoma in situ.