These differences in TGF-β1 and VEGF were due to greater platelet degranulation, since PF4 levels were higher in lung cancer cases than controls (P = 0.02), and residual serum levels did not differ between lung cancer cases and controls (P = 0.40 for TGF-β1, P = 0.15 for VEGF; Table2). Here, PF4 is linked to lung cancer.