Fig. 4

Alteration of mitochondrial membrane potential by the treatment of low-intensity ultrasound combined with 5-FU. a Representative mitochondrial membrane potential (Δψm) in BEL-7402 cells after the treatment. b The relative level of Δψm by the fluorescent intensity quantified with IOD values. Data was presented as the mean ± SD (n = 6, ^★ p < 0.05 vs. other three groups; ^★★ p < 0.05 NAC-treated vs. NAC-untreated US + 5-FU group)