This in-vitro study exposed primary cortical neurons and human immortalized skin fibroblasts to simultaneous 5G-modulated 3.5 GHz and GSM-modulated 1.8 GHz RF-EMF at SARs of 1 or 4 W/kg. It reports no significant changes in neuronal network firing/bursting activity and no alteration of mitochondrial ROS in fibroblasts. Stress-related signaling readouts showed only minor, threshold-level variations without a consistent pattern, and no HSF1 activation was observed. Overall, the authors conclude there is no strong evidence of biological effects under these exposure conditions.