In microfluidic devices, continuous low flow cigarette exposure to non-tumor bronchial epithelial cells in chronic obstructive pulmonary disease (COPD) and lung squamous cell carcinoma patients stimulates ROS production and induces tumor-like transformation of human non-tumor bronchial epithelial cells through GRP78, NF-κB, and PI3K signaling pathways [34]. This evidence concerns the gene PIK3CG and chronic obstructive pulmonary disease.