FOLR1 and cancer: In the 2D killing assay, coculturing of FRα-CAR-T cells (E) with FRα expressing-target cancer cells (T), MDA-MB-231 and HCC70 cells (Additional file 2: Fig. S2) at E:T of 0.5:1, 1:1, and 2.5:1 reduced fluorescence intensity of viable target cells, with a significant reduction level at only 2.5:1 (P < 0.01) (Fig. 5A, B).