SMAD4 and neoplasm: The mutation allelic frequencies (MAFs) of KRAS (r = 0.55), TP53 (r = 0.49), CDKN2A (r = 0.64), SMAD4 (r = 0.69), and ARID1A (r = 0.93) in the tumor and blood samples were significantly correlated with each other in a linear manner (Fig. 1B).