Fig. 1From: Visualization of the spatial and temporal dynamics of MAPK signaling using fluorescence imaging techniquesSchematic diagrams of conventional MAPK signaling cascades. Mammalian cells simultaneously express several subfamilies of MAPK cascades. They include the growth-promoting extracellular-signal regulated kinase (ERK) family and the growth-suppressing stress-activated protein kinase (SAPK) families, the JNK and p38, and the relatively recently discovered ERK5. The ERK family cascade consists of a three-tired kinase cascade of a MAP3K (Raf), MAP2K (MEK) and MAPK (ERK). Activation of a small-G protein Ras triggers the activation of Raf and thus begins the cascade. Similarly, a wide variety of stresses activates the SAPK cascades via diverse stress MAP3Ks and their activators. Although there are at least 14 stress MAP3Ks, many fewer MAP2Ks (MKK3/4/6/7) and MAPKs (p38α/ß/γ/δ and JNK1/2/3) function in the stress response pathway. The activators of stress MAP3Ks include the small-G proteins (Rac, Rho and Cdc42), TRAFs and GADD45s. The MEK5-ERK5 pathway is also activated by several types of stresses and growth factors and shares some stress MAP3Ks (MEKK2/3) with JNK and p38. Arrows indicate the activation signal. Abbreviations used in this figure are as follows: MEK MAPK/ERK kinase, MEKK MEK kinase, MLK mixed-lineage kinase, TAK1 transforming growth factor ß-activated kinase, MTK1 MAP three kinase 1, ASK apoptosis signal-regulating kinase, TAO thousand and one amino-acid kinase, Tpl tumor progression locus, TRAF tumor necrosis factor receptor-associated factor, GADD growth arrest and DNA damage-inducible proteinBack to article page