DDR2 and non-small cell lung carcinoma: According to the median ratio of relative DDR2 expression (1.76) in tumor tissues, the 56 NSCLC patients were classified into two groups: High-DDR2 group (n = 27, DDR2 expression ratio ≥ median ratio) and Low-DDR2 group (n = 27, DDR2 expression ratio ≤ median ratio).