PBK and osteosarcoma: TOPK mRNA was significantly elevated in osteosarcoma tissue samples (40.8 ± 27.0 TPM, P < 0.001) and cell lines (101.0 ± 68.7 TPM, P < 0.001) compared with normal tissues (0.13 ± 0.22 TPM) (Fig. 1B).