The staining results showed that cyclin E1 was located in both the osteosarcoma cellular nucleus and cellular cytoplasm, whereas it was located only in the cellular nucleus of the human normal osteoblastic hFOB 1.19 cell line, which indicated that different cyclin E1 isoforms with individual distributions existed in osteosarcoma (Figures 1B, C; Supplementary Figure S1). This evidence concerns the gene CCNE1 and osteosarcoma.