ERK1/2 is both a therapeutic target and a key pharmacodynamic biomarker across RAS-, RAF-, and MEK-directed programs — but phosphorylation status alone doesn't tell you whether the enzyme is active. This white paper shows how AQT1076, a PhosphoSens® sensor peptide selective for ERK1/2, delivers a continuous, quantitative activity readout from purified enzyme through crude lysate.
Download this white paper to discover:
- How AQT1076 achieves selective ERK1/2 detection across a 407-kinase selectivity panel
- How Sino Biological's tag-free and GST-tagged recombinant ERK1/2 support assay characterization
- How ERK1/2 activity is quantified directly in cell lysates following pathway stimulation
- How a continuous activity readout complements pERK Western blotting in RAS/MAPK research
Does ERK1/2 phosphorylation reflect true kinase activity? An independent study says no.
Researchers at the Hebrew University of Jerusalem tested five clinical-stage ERK1/2 inhibitors — BVD523, GDC0994, SCH772984, ASN007, and Temuterkib — across transformed and cancer-derived cell lines. Every inhibitor blocked ERK's catalytic output while lifting the negative feedback that normally suppresses ERK phosphorylation at the TEY motif. Western blot signal went up. Real kinase activity, measured directly with the PhosphoSens-Lysate ERK1/2 kinase activity assay, stayed firmly suppressed.
Darash-Yahana, M., Soudah, N., Baskin, A., Levy-Saar, I., Levitzki, A., & Engelberg, D. (2026). Erk inhibitors intercept Erk-mediated negative feedback while imposing cell-cycle arrest and activating p38. iScience 29, 116629.
ERK1/2 Catalytic Activity (RFU/min)
Where a Direct ERK1/2 Activity Readout Changes the Answer
Confirm a compound is suppressing catalytic output, not just triggering a feedback-driven rise in phospho-signal — and distinguish true target engagement from resistance.
Track real-time pathway suppression or reactivation after dosing, with continuous activity data that a fixed-timepoint western blot can't capture.
Compare functional ERK1/2 activity across cell lines, patient-derived samples, or genetic variants under identical conditions — no antibody re-optimization required.
The Numbers Above, From AQT1076's Own Validation Report
Shown here: lysate titration data confirming a 32-fold linear range (78–2,500 ng, r² = 0.9714) using lysate from PDGF-stimulated NIH-3T3 cells. It's one figure from AQT1076's full assay validation report, which also covers the 407-kinase selectivity screen, the 10-fold PDGF activation data, and SCH772984 blocking across 7 cell lines.
Read the Full Validation ReportThe same AQT1076 sensor peptide behind this white paper, in a ready-to-run kit for measuring endogenous ERK1/2 activity directly in your own cell or tissue lysate — no antibodies, no wash steps.
- AQT1076 sensor peptide substrate
- Recombinant ERK1/2 enzyme control
- ATP, EGTA & DTT
- Reference inhibitor compound
- PhosphoPreserve cell extraction buffer
- Protease & phosphatase inhibitor cocktails
- Reaction & dilution buffers
- Assay controls
