Fig. 1

Cell growth curve and clonogenic curve of nasopharyngeal carcinoma (NPC) cell lines after evofosfamide treatment. a Cells were treated with evofosfamide for 24 h under hypoxia or normoxia and then cultured without drug for up to 48 h. Cytotoxicity was assessed by the cell counting kit-8 (CCK-8) assay, and the 50% inhibition concentration (IC₅₀) values were calculated. The IC₅₀ values and hypoxia cytotoxicity ratio (HCR) (normoxia versus hypoxia) are shown in Table 1. b Cells were treated with evofosfamide for 6 h under hypoxia or normoxia and then cultured without drug for 7–10 day. The clones were fixed and stained with crystal violet. Colonies of more than 50 cells were counted and the survival fractions were calculated. *P < 0.05, **P < 0.01