Fig. 4.

Activating NOTCH1 mutations promote BCR signaling, proliferation, angiogenesis and enhance tumor cell migration upon DLL4-stimulation that can be abolished by treatment with OMP-52M51. a Effect of DLL4-stimulation and treatment with OMP-52M51 on ERK and MEK phosphorylation. Mino and JeKo-1 MCL cells were stimulated with DLL4 (4 μg/mL) and treated with OMP-52M51 or IgG2. After 48 h, protein expression of p-ERK, total ERK1, p-MEK1/2 and total MEK1/2 was assessed by Western Blot [n = 3; one representative experiment is shown]. b Relative cell proportion in G₂-G_M phase of cell cycle in Mino and JeKo-1 cells stimulated or not with DLL4 and treated with OMP-52M51 or IgG2 for 48 h. Cell cycle phases were measured by flow cytometry using propidium iodide and analysed using FlowJo software (n = 4, *p = 0.0286, bars represent the mean ± SD). c Mino and JeKo-1 cells were stimulated with DLL4 and treated with OMP-52M51 or IgG2 for 48 h. Migration of cells was assessed in a transwell system with inserts of 8 μm pore size. Migration was defined by counting the cells that migrated to the lower chambers containing medium with the chemoattractant CXCL12 (200 ng/mL) (n = 5, **p = 0.0079, bars represent the mean ± SD). d Cells were stimulated with DLL4 and treated with OMP-52M51 or IgG2 for 48 h. Supernatants were then harvested and added to HUVEC. After 24 h, the number of branch points was quantified as the mean of five randomly chosen fields from each well. Pictures were taken with a DM IL LED microscope coupled to a DFC295 camera (magnification 100x) (n = 5, bars represent the mean ± SD, *p = 0.05; ***p = 0.001). Microscope images from one representative experiment are shown