PathScan^® Stress and Apoptosis Signaling Antibody Array Kit (Fluorescent Readout) #12923

Cell death can occur due to a variety of circumstances including nutrient deprivation, inability to generate or store the energy required for metabolic functions, or deleterious environment that causes irreparable damage. Cells integrate multiple signals from a variety of sources before following either pro- or anti-apoptotic pathways. These signals can often carry conflicting information. Assessing the net effect of these processes in cell populations can be achieved by monitoring changes in a number of key signaling components. The caspase-3 and caspase-7 proteases exert a pro-apoptotic function through cleavage of multiple cellular targets. Caspase-3 and caspase-7 are activated by cleavage at Asp175 and Asp198, respectively. PARP is a DNA repair and apoptosis enzyme that is inactivated by cleavage at Asp214 by caspase-3 or caspase-7. HSP27 is a mediator of cell stress that confers resistance to adverse environmental conditions. HSP27 is activated by phosphorylation at Ser82. Chk1 and Chk2 kinases act downstream of ATM/ATR and play an important role in DNA damage checkpoint control. Activation of Chk1 and Chk2 involve phosphorylation at Ser345 and Thr68, respectively. Tumor suppressor p53 plays an important role in cellular response to DNA damage. p53 is phosphorylated at Ser15 by ATM/ATR or DNA-PK leading to its accumulation. Smad2 is a key mediator of TGF-β signaling. Stimulation by TGF-β leads to Smad2 phosphorylation at Ser465/467 and translocation of Smad2 into the nucleus. The outcome of TGF-β signaling is context dependent and can either induce apoptosis or contribute to tumor cell metastasis. Activation of NF-κB/Rel occurs through a proteasome-mediated degradation of IκBα. The inhibitor IκBα is targeted to the proteasome via phosphorylation of IκBα at Ser32 and Ser36. NF-κB activation is triggered by a diverse group of extracellular signals promoted by inflammatory cytokines, growth factors, and chemokines. TAK1 is a kinase that can be activated by TGF-β, bone morphogenetic proteins and other cytokines. Activated TAK1 phosphorylates MKK4, MKK3/6, and NIK. Phosphorylation of TAK1 at Ser412 is one of the mechanisms that regulate the levels of its activation. Cellular stress such as viral infection, endoplasmic reticulum stress, and amino acid deprivation leads to phosphorylation of eIF2α. Phosphorylation of eIF2α at Ser51 in response to cellular stress leads to a reduction of protein synthesis. The ERK1 and ERK2 MAP kinases are major signaling nodes that have many substrates and primarily transmit growth and proliferation signals. The ERK MAP kinase is activated by a dual phosphorylation of Thr202 and Tyr204. p38 MAPK and SAPK/JNK MAP kinases are activated through a similar dual phosphorylation mechanism in response to pro-inflammatory cytokines and genotoxic stress. Akt is activated by stimulation of growth-factor receptors and primarily promotes anabolic growth and survival signals via targeting its broad array of substrates. Akt phosphorylates Bad at Ser136 and inhibits its ability to induce apoptosis. Survivin is an anti-apoptotic protein that is highly expressed during fetal development and cancer cell malignancy. Survivin binds and inhibits caspase-3, controlling the cell cycle by inhibiting apoptosis and promoting cell division. α-tubulin is a building block of microtubules that are present in all eukaryotic cells. The levels of the globular α-tubulin are considered to remain relatively constant. Therefore, assessing the relative levels of α-tubulin may assist with signal normalization between the various samples.