FOLR1 and squamous cell carcinoma: When we searched the Gene Expression Omnibus (GEO) datasets for radioresistant cancer cells and FRα, we found that FRα was downregulated in radioresistant B-precursor acute lymphoblastic (ALL) tumor cells and the radioresistant squamous cell carcinoma cell line SCC61 (Supplementary Figure 8), suggesting that the downregulation of FRα in radioresistant cancer cells might be a universal phenomenon.