HELLS and osteosarcoma: Further analyses of HELLS gene expression using real-time qPCR in human osteosarcoma cell lines (143B, SJSA-1, SaOS-2, and U-2 OS) and patient derived xenografts (PDX1-5) showed a significant upregulation of HELLS mRNA level in most osteosarcoma samples when compared to human mesenchymal stem cells (MSCs) (Figure 2B–2C).