Fig. 5. The synergistic effect from Notch 1 ICD and SMAD1 is dose-dependent and partially CSL-dependent. (A) Transfection of Notch 1 ICD and variable amounts (100, 200 and 300 ng) of SMAD1 in COS-7 cells, in the absence (white bars) or presence (black bars) of exogenous BMP4 (50 ng/ml), measured by activation of a Hey1-luciferase reporter construct. (B) An experiment similar to that in A, carried out in the absence of exogenous BMP4, with 100 and 200 ng SMAD1. Shown below is a western blot for Notch 1 ICD and SMAD1. (C) Transfection of Notch 1 ICD (67 ng), SMAD1 (67 ng) and/or R218H CSL (67 ng) in COS-7 cells, in the absence (white bars) or presence (black bars) of exogenous BMP4 (50 ng/ml), measured by activation of a Hey1-luciferase reporter construct.