CCNE1 and osteosarcoma: To determine whether QSOX2 is a cell cycle-related protein, a dataset from the GEO database (GSE52100) containing cell cycle-regulated mRNA transcripts from the entire genome of the osteosarcoma-derived U2OS cell line was downloaded, and we compared the expression levels of QSOX2 and classic periodic marker genes (CCNE1, CCNE2, CCNA1, CCNB1, and CCNB2) in different phases of cell cycle progression after double thymidine block release.