CXCR4 and neoplasm: In addition, pretreatment of AsPC-1 cells with BsNb PX4 or Nb CXCR4 resulted in a negative impact on cell proliferation, which indicated that the inhibitory effect of BsNb PX4 on tumour cells might involve blocking the CXCL12/CXCR4 signalling pathway (Fig. 3e).