Fig. 1

Dominant contribution of p50 and p52 in the constitutive NF-κB activity in HL cells. a Left: RNAi-mediated knockdown (KD) of NIK (MAP3K14). L1236 cells were incubated with siRNA against MAP3K14 and harvested 1 day after the end of the siRNA treatment. Protein levels of the precursor proteins p105 and p100, their products p50 and p52, as well as phospho-Ser-866/870-p100 and phospho-Ser-933-p105 were analyzed in whole extracts by western blot (WB). CDK4 was used as loading control. Right: EMSA analysis of L1236 whole cell extracts after KDs of single NF-κB subunits and double KD of p50 and p52. Control of KD efficiencies is shown in Additional file 2: Figure S1B. b WB analysis of nuclear (N) and cytoplasmic (C) distribution of NF-κB subunits in HL cell lines, as indicated (top labels). p105 and PARP1 serve as purity controls for nuclear and cytoplasmic extracts, respectively. c Immunohistochemical detection of p105/p50 and p100/p52 in representative biopsies from HL patients. Arrows indicate nuclear abundance of p50 (left panel) and p52 (right panel) in malignant Reed-Sternberg cells compared to surrounding benign cells. A total of 20 biopsies were used, all were stained for p105/p50 and 18 biopsies were stained for p100/p52