Phospho-p44/42 MAPK (Erk1/2) (Thr202/Tyr204) Recombinant Rabbit mAb (SDT-5119)

Phospho-p44/42 MAPK (Erk1/2) (Thr202/Tyr204) is the activated form of extracellular signal-regulated kinases 1 and 2 (ERK1/2) following phosphorylation at specific sites, specifically referring to the simultaneous phosphorylation of threonine and tyrosine residues at positions 202/204 of ERK1 (corresponding to positions 183/185 of ERK2, using the classic dual-site designation). This phosphorylation event is specifically catalyzed by the upstream kinases MEK1/2 and serves as a core hallmark of activation of the canonical Ras-Raf-MEK-ERK signaling pathway. Once activated by phosphorylation, p-ERK1/2 translocates to the nucleus, where it phosphorylates and regulates various downstream substrates, including transcription factors (such as Elk-1, c-Fos, and c-Myc) and cell cycle regulatory proteins, thereby participating in the regulation of key cell fate decisions including proliferation, differentiation, survival, migration, and apoptosis. This phosphorylation modification is tightly regulated and, under normal physiological conditions, responds to extracellular stimuli such as growth factors, cytokines, and mitogens. In various pathological states, particularly in more than one-third of malignant tumors (such as melanoma, colorectal cancer, and pancreatic cancer), the phosphorylation level at these sites is often persistently and abnormally elevated due to upstream activating mutations (e.g., RAS or BRAF mutations), driving uncontrolled tumor cell proliferation and metastasis. Therefore, detecting the level of Phospho-p44/42 MAPK (Thr202/Tyr204) not only serves to assess the activation status of the ERK signaling pathway but also acts as a key biomarker for screening the efficacy of MEK/ERK-targeted inhibitors and monitoring resistance mechanisms.