Early Growth Response Protein 1 (EGR1) is a zinc-finger transcription factor that plays a pivotal role in various cellular processes. It is rapidly and transiently induced in response to a wide range of extracellular stimuli, including growth factors, cytokines, oxidative stress, and neuronal activity. This immediate early gene product acts as a molecular switch, regulating the expression of downstream target genes involved in cell proliferation, differentiation, apoptosis, and synaptic plasticity. To test the effect of EGR1 on cell proliferation, SKOV3 cells were seeded into triplicate wells of 96-well plates and allowed to attach, replaced with various concentrations of recombinant mouse EGR1. After incubated for 72h, cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10 µl of CCK-8 solution was added to each well of the plate, then the absorbance at 450 nm was measured using a microplate reader after incubating the plate for 1-4 hours at 37 ℃. Cell viability was assessed by CCK-8 assay after incubation with recombinant mouse EGR1 for 72h. The result was shown in Figure 1. It was obvious that EGR1 significantly decreased cell viability of SKOV3 cells. The ED50 of recombinant mouse EGR1 is 2.836 μg/ml.