The CL1-5-binding ability of PC5-2 was further confirmed by a peptide competitive inhibition experiment using immunofluorescent staining. The results showed that the binding activity of the PC5-2 phage to CL1-5 cells was inhibited by the synthetic peptide SP5-2 in a dose-dependent manner. At a concentration of 27 mg/ml, SP5-2 completely inhibited the binding activity of PC5-2 (Fig. S1 ). The control phage did not bind to CL1-5 cells, and PC5-2 did not bind to NPC-TW01 in this assay ( Fig. S1 and Text S2).