The p42 protein often refers to a specific isoform of the mitogen-activated protein kinase (MAPK) pathway, particularly p42 MAPK, which is also known as extracellular signal-regulated kinase 2 (ERK2). This protein plays a crucial role in various cellular processes, including proliferation, differentiation, and survival.
The activation of p42 MAPK has been associated with various types of cancer, including melanoma, breast cancer, and colorectal cancer.
p42—which is commonly used to refer to the ~42 kDa isoform of extracellular signal‑regulated kinases (ERK), often designated as ERK2 (p42 MAPK)—in cancer. This summary covers its expression trends, prognostic implications, and functional roles in tumor biology. Note that the MAPK/ERK pathway is complex and highly context‑dependent, with ERK2 (p42) frequently working in concert with its counterpart ERK1 (p44) to regulate diverse cellular processes.
In many cancers, the MAPK/ERK pathway is hyperactivated due to upstream mutations (e.g., in RAS or BRAF), leading to increased levels of active (phosphorylated) p42.
– While the total expression of ERK2 may be relatively stable, the activated/phosphorylated form is frequently elevated, reflecting increased signaling activity.
– This activation is observed in a variety of cancers including melanoma, colorectal cancer, lung cancer, and thyroid cancer.
p42 is not exactly the same as "ERK" in general but is closely related. In many contexts, p42 refers specifically to the 42‑kDa isoform of the extracellular signal-regulated kinases (ERKs), often known as ERK2. Typically, cells express two closely related isoforms of ERK: one is about 44 kDa (ERK1, sometimes called p44) and the other is about 42 kDa (ERK2, or p42). Both of these are members of the mitogen-activated protein kinase (MAPK) family and play key roles in cellular signaling.
So, when someone refers to p42 in the context of MAPK signaling, they are usually talking about ERK2, whereas "ERK" can be used to refer to both isoforms (ERK1 and ERK2) collectively.
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