ERBB2 and cancer: At the next level of characterization (Level 3), finer groups of cancer epithelial heterogeneity emerge with clusters exhibiting decreased mitotic spindle activity (cluster 0), decreased TNFA signaling (cluster 20), increased EMT activity (cluster 13), as well as subtype-specific clustering (Luminal A: 1~17, 18; Luminal B: 6, 5, 15, 16; HER2: 3, 14), and grade specific clustering (high grade tumors: 8; low grade tumors: 6, 5, 18).