Abstract: Objective  To investigate the mechanism of neurofibromin 1 (NF1) in gallbla-dder cancer. Methods  The experimental study was conducted. Human gallbladder cancer cell lines, including GBC-SD, NOZ, SGC996, EH-GB1, ZJU0428, human embryonic kidneys cell line 293T and human cervical cancer cell line HELA, were cultured. The recombinant plasmids (mRFP-YAP1FL-FLAG and eGFP-MYC-NF12650?2750-HA) were constructed for co-immunoprecipitation experiment. The truncated Yes associated protein 1(YAP1) and NF1 recombinant proteins were purified in vitro. The interaction between NF1 and YAP1 in vitro or in vivo were verified by isothermal titration calori-metry (ITC) assay, GST pull-down experiment, co-immunoprecipitation, immunofluorescence, laser confocal microscopy, and the expression of NF1 protein in different gallbladder cancer cell lines was verified by Western blot experiments. Observation indicators: (1) interaction between NF1 and YAP1 in vitro; (2) interaction between NF1 and YAP1 in cells; (3) expression of NF1 protein in different  human gallbladder cancer cell lines. The dissociation constants were exported from ITC 200 software and represented as Mean±SD. Count data were represented as absolute numbers. Results  (1) Interaction between NF1 and YAP1 in vitro. ① Results of ITC assay showed that there was interac-tion between PPQY and YAP1-WW1, between PPQY and YAP1 (Amino acid residues 162?275), and the dissociation constants between PPQY and YAP1-WW1, between PPQY and YAP1(Amino acid residues 162?275) were (0.42±0.06)mmol/L, (0.69±0.14)mmol/L, respectively. ② GST pull-down results indicated that the target protein His-Sumo-YAP1WW1 was obviouly observed in protein lane of reaction system between GST-PPQY recombinant protein and His-Sumo-YAP1WW1, relative to the reaction system between GST protein and His-Sumo-YAP1WW1. The target protein His-Sumo-YAP1WW2 was obviouly observed in protein lane of reaction system between GST-PPQY recombinant protein and His-Sumo-YAP1WW2, relative to the reaction system between GST protein and His-Sumo-YAP1WW2. (2) Interaction between NF1 and YAP1 in cells. ① Co-immunoprecipitation results indica-ted that NF1 protein was observed in cell lysis solution which was incubated by FLAG gel beads and cotransfected with mRFP-YAP1FL-FLAG and eGFP-MYC-NF12650?2750-HA. ② Immuno-fluorescence and laser confocal microscopy results indicated that YAP1 and NF1 with obvious fluorescence were co-localized in the cytoplasm of human gallbladder cancer NOZ cells. However, YAP1 with obvious fluorescence was localized in the nucleus of human gallbladder SGC996 cells and NF1 showed weak fluorescence. (3) Expression of NF1 protein in different human gallbladder cancer cell lines. Western blot results showed that with the expression level of NF1 protein in HELA cell line as the standard, the relative expression levels of NF1 protein in EH-GB1, GBC-SD, NOZ, SGC996, ZJU0428 cell lines were 1.28, 0, 1.01, 0, 0, respectively. Conclusion  NF1 affects the gallbladder cancer by directly acting on YAP1 protein.