Our flow cytometry analysis demonstrated that neither Wnt3A or Rspo2 alone nor the combination treatment had any effect on the enrichment of CD133+ positive cells in U251 (Additional file 1: Fig S2B), suggesting that Rspo2/Wnt3A enhances stem cell traits in GSCs rather than enlarges the GSC pool within GBM cells. Here, RSPO2 is linked to glioblastoma.