S100A9 and acute kidney injury: However, other critical immune transcripts and pathways were also highly upregulated including the S100a8/S100a9 pathway noted in AKI [77]; cytokines Il17f, Il24, Il33, and Tnf pathways in kidney injury [78,79,80]; the arachidonic acid metabolite binding Ltb4r1 and Ltb4r2 pathway [81] and the Lilrb4a,b receptor pathway, both involved in leukocyte recruitment [82,83]; the chemoattractant Cxcr4 [84] and pathway activation by the anaphylatoxin, Hc (C5a) [85]; and the prostanoid-producing Ptgs2 transcript (Cox2) pathway [86].