Drugs such as nicotine and cocaine activate a group of dopamine-producing neurons in the VTA.
One possible reason, they discovered, is that calorie restriction and exercise activate a group of genes called sirtuins, which appear to have a direct effect on longevity.
Apoptotic signals, both intracellular and extracellular, converge to activate a group of apoptosis-specific proteases termed caspases, a family of cysteine proteases with specificity for aspartic acid residues in their substrates [8].
As ATF-2 is also activated by hypoxia (Maekawa et al. 2008), it may activate a group of target genes, including the PDGF receptor α, in response to hypoxic stress.
6, 7 Upon ER stress, a variety of human cancers activate a group of signal transduction pathways, inducing cellular stress responses such as the unfolded protein response (UPR) and autophagy to maintain ER homeostasis.
ATF4 is a transcriptional factor which senses deficits in protein translation, typically related to ER stress or amino acid limitation, and in turn activates a group of target genes through a consensus ATF4 promoter binding motif (Harding et al., 2003; Su et al., 2009).
3-phosphoinositide-dependent protein kinase 1 (PDK1), a serine/threonine kinase, can activate a group of protein kinases belonging to the AGC kinase family, including protein kinase A, protein kinase G and protein kinase C. PDK1 has pivotal roles in mediating energy metabolism, cell proliferation and migration.
Apoptotic signals may arise from a variety of stimuli, but both the extrinsic and intrinsic pathways converge to activate caspases, a group of proteolytic enzymes that cleave their substrates at specific residues [ 4].
LCO signals are transduced via a common symbiotic signaling pathway (CSSP) that activates a group of GRAS transcription factors (TFs).
