Then, the heat map displays the expression levels of the top 10 upregulated (PANX3, HAPLN1, UCHL1, STEAP1, COMP, EPYC, TREM2, COL10A, GJB2 and COL11A1) and downregulated (LCN2, S100A8, S100A12, HEMGN, CA1, HBD, DEFA4, MPO, CLC and LTF) genes in osteosarcoma group compared with normal group (Fig. 1B). This evidence concerns the gene MPO and osteosarcoma.