Scientists have found a natural inhibitor of immune activity which may be the most important factor in the fight against tumors. This may help make cancer immunotherapy more effective and to find new treatment ways for oncological illnesses. With the help of natural “brake” mechanisms, the human immune system prevents too much autoreaction and inflammation in healthy tissues. Cancer cells benefit from this, which causes them to avoid colliding with immune cells and reduces the activity of the immune system as a whole. A group of scientists in the USA has discovered a new and very important “brake” of immunity-EGR4 molecule. The experiments have shown that when removing EGR4 from immune cells, the brake of immunity slows down which allows the killer cells to be active. T-cell activity, in turn, increases anti-tumor immunity and allows attacking better to cancer cells. The scientists found that EGR4-suppressed mice had less tumor growth and less metastasis. No such improvement was observed in the control group (when normal expression occurred). According to scientists, EGR4 has great potential to improve anti-cancer treatment. For example, removing the EGR4 molecule from a T-cell in a cancer patient and then returning it to the body can increase the effectiveness of existing immunotherapeutic approaches.