HOXB4 and gastric cancer: Discretization of GRNs identified OVOL2, an epithelial lineage determinant in C3 [18]; HOXB4, a regulator of ovarian cancer progression and embryonic stem cell differentiation in C5 [19,20,21]; KLF9, an inhibitor of gastric cancer invasion and androgen-dependent prostate cancer growth in C5 [22,23]; ATF3, a stress-regulated signal in metabolism, immunity, and oncogenesis in C6 [24]; and STAT2, a regulator of proliferation, metastasis, and chemoresistance in C6 [25,26,27,28].