Fig. 1

B cell receptor signaling pathway with receptors, inhibitors, targets, and other molecules. B cell receptor signaling mediates the canonical pathway for nuclear translocation of the transcription factor NF-κB. Initial activation of the B cell receptor activates Src family kinases and the Syk and Btk tyrosine kinases, which form a signalosome complex with other signaling enzymes and proteins. Btk phosphorylates and activates PLCγ2, which yields the downstream molecules inositol-1,4,5-triphosphate (IP3) and diacylglycerol (DAG) and sensitizes PKCβ due to release of calcium ions. The activated PKC leads to formation of the CBM complex; the IKK complex is then activated, which phosphorylates IκB, allowing it to be ubiquitinated and proteasomally degraded. The p50 and p65-RelA NF-κB heterodimer is then released into the nucleus to induce gene expression