S100A9 and metastatic melanoma: Increased expression of the two downstream regulators of ID1, S100A8 and S100A9 levels was also observed (1.8- and 1.7-fold higher and up to 3.1- and 2.7-fold, respectively) in CD11B+ PBMCs from patients with metastatic melanoma compared with healthy, age-matched controls (unpaired t-test, P<0.01; Fig. 7b,c).