RB1 and neoplasm: RB1, another key tumor suppressor, is involved in the control of G1/S cell cycle transition, and its loss is associated with poor prognosis and increased metastatic potential in osteosarcoma [33].Although the absolute expression level of PDK1 was lower than that of these canonical markers, the parallel expression patterns suggest that PDK1 may act in concert with these proteins, contributing to the regulation of cell proliferation and tumor progression.