Figure 6.

Schematic representation of the effect of paclitaxel (PTX) and MG132 on the NF-κB signaling pathway in breast cancer cells. PTX phosphorylates and activates the IκK complex, leading to the phosphorylation, ubiquitination, and degradation of IκBα. This frees NF-κB, which is then activated and translocated to the nucleus, thereby activating transcription of multiple downstream genes. This leads to an increased expression of proteins related to cell cycle, apoptosis, migration, and invasion, and decreases apoptosis. MG132 inhibits the degradation of IκBα, thereby inhibiting activation and output of NF-κB signaling, possibly by targeting IκBα and decreasing the nuclear and cytoplasmic levels of NF-κB. This leads to a decreased expression of proteins related to the cell cycle, apoptosis, migration, and invasion, and increases apoptosis. Stimulatory events are indicated with green arrows. Inhibitory events are indicated with red lines ending in bars.