Updated project metadata. Glioblastoma is the most common primary brain cancer and is associated with poor survival and high rates of recurrent diseases. The median survival using standard radio-chemotherapy is 15 months and the 5-year survival rate is below 5%. It is hypothesized that treatment resistance, diffuse infiltration of the brain and disease recurrence is, at least in part, due to cancer cells that can obtain a transient, stem-like phenotype. These so-called glioma stem-like cells (GSCs) display pluripotency, express marker proteins associated with stem-cells and can replenish the tumor after treatment. Recently, we have shown that the hormonally active form of vitamin D3, calcitriol (1α,25(OH)2-vitamin D3), is active in a subset of GSCs and reduces traits of stemness. Here, we have employed a set of 8 GSCs that do not respond to calcitriol-treatment (No-responder) and the 8 strongest responders to calcitriol (High-responder) and compared to proteomes after treatment with 50 nM calcitriol for 48h.