In the search for noninvasive biomarkers for the early diagnosis of pediatric ALL by assessing serum proteomic profiles, Shi et al. reported that platelet factor–4 (PF4), an indicator of megakaryocyte maturation and differentiation, and platelet activation and pro-platelet basic protein precursor (PBP) were found to be down-regulated in ALL patients [43]. The gene discussed is PF4; the disease is acute lymphoblastic leukemia.