Verapamil inhibits expression of HWP1. Strain NKF152 was incubated in RPMI-1640 medium containing different concentrations of verapamil (μg mL⁻¹), and GFP fluorescence density of the culture was determined for the indicated times. *Significant difference between the control group (0) and the verapamil-treated groups (P< 0.05).