Effects of 3-hydroxyflavone (3-HF), 3,2′-dihydroxyflavone (3,2′-DHF), 3,3′-DHF, and 3,4′-DHF on USC isolation efficiency. (A) Structures of the flavonoids 3-HF, 3,2′-DHF, 3,3′-DHF, and 3,4′-DHF. (B) Pictures of USCs treated with 3-HF, 3,2′-DHF, 3,3′-DHF, and 3,4′-DHF and stained with crystal violet after 14 days. (C) Relative cell number of isolated USCs after 14 days to the cell number of control (no treatment on gelatin coated plate) set to 1. (D) Growth curve of 3-HF-, 3,2′-DHF-, 3,3′-DHF-, and 3,4′-DHF-treated USCs at different time points. (E) Relative cell number of isolated USCs after 14 days incubation treated with 3,2′-DHF, 3,4′-DHF and/or Y-27632 + Matrigel compared to the number of cells of gelatin group control set 1. n = 3 biological samples. (* p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001).