Notch2 is a major part of C1 in B-CLL cells.

(A) A cold oligonucleotide (CBF1.Cp) spanning a well-characterized CBF1 site derived from the EBV C promoter competes with probe B (and also with probe A, C, D; data not shown) for binding to C1. (B) A 20-bp oligonucleotide (CBF1.2; −130 to −149) spanning CBF1 site 2 competes with probe A for binding to C1. (C) Supershift assay showing that Notch2IC is a component of C1 in B-CLL cells and in Th cells. (D) Including antibodies specific for Pax5 (BSAP) diminished the signal of C2. (E) A higher order complex (arrow) is visible with probe C (lane 2) but not with probe B (lane 1), indicating that C1 and C2 bind the shared DNA regions in a cooperative manner.