S100A9 and neoplasm: An important role of signals transmitted from primary tumor cells (e.g. cytokines) in the stimulation of pro-inflammatory members of the S100 family (S100A8/S100A9) and FN followed by attraction of immune cells and their progenitors from bone marrow to the site of metastasis and the formation of “pre-metastatic” niches were recently reported [49], [50].