PPBP and Sepsis: When comparing sepsis subgroups based on their outcomes, five key protein markers—β-actin (ACTB), C-X-C motif chemokine 7 (CXCL7), platelet factor 4 (PF4), fibronectin (FINC), and Metalloproteinase Inhibitor 1 (TIMP1)—were identified as significant discriminators (Fig. 2).