Elevated levels of both PTEN and PTENP1-S were notable in certain malignant tumors, such as osteosarcoma cell lines [64] and melanoma cell lines [63], whereas decreased levels of PTEN and PTENP1-S were observed in other samples, such as prostate cancer tissues and gastric cancer cell lines [17, 65]. This evidence concerns the gene PTEN and osteosarcoma.