TP53 and neoplasm: However, the somatic genome of the OS is considered complex and characterized by tumor heterogeneity [16,17]; indeed, an increased number of mutations, not only in TP53 or RB1 genes, but also in genes that are part of the Wnt signaling pathway, such as APC (adenomatous polyposis coli) and β-catenin, have been associated with OS.