Surface markers, such as CD133, are commonly used to identify CSCs; however their biological function in osteosarcoma is unclear and suitable markers for separating OSCs from differentiated cells remain to be found [17]. Gemei et al. detected 50 out of 245 membrane proteins that were differentially expressed between OSCs and differentiated cells through gene expression profiling. Their results have provided valuable data towards defining a cell-surface protein signature for OSC [18].
Fig. 1 provides a schematic illustration of these markers in OSCs; Table 1 summarizes their functions.