By enzyme-linked immunosorbent assay (ELISA), the concentration of CXCL1 was found to be significantly higher in CAF medium compared with that in matched NF medium (CAF-1: 9321.99 pg/ml; NF-1: 1174.33 pg/ml; P=0.0245; CAF-2: 25353.47 pg/ml; NF-2: 9132.01 pg/ml; P=0.0216), while extremely low in the culture medium of tumor cells (Figure 1c). This evidence concerns the gene NF1 and neoplasm.