In line with 2-DE and WB profiling, TMA-based immunohistochemistry revealed that CTSD was increased in osteosarcomas (p = 0.0237) and pulmonary metastases (p = 0.0079) compared to normal bone tissue and showed a significant regulation in the three group comparison (p = 0.0391). This evidence concerns the gene CTSD and osteosarcoma.