COL1A1 and neoplasm: Together, we screened tumor differentiation grade-related genes prognostic signature including NFAIP2, MAGEA3, CXCR4, COL1A1, FN1, VCAN, PXDN, COL5A1, MUC13 and RGS2, and provided evidence of GC heterogeneity based on single-cell RNA-seq.