Besides, we also investigated the protein levels of epidermal growth factor receptor (EGFR) among the four clusters since an increasing body of evidence highlighted its unique role in driving the stratification of landscapes of immune infiltration in various types of cancers (24–26) and found significantly higher expression of EGFR in cluster A1 than in cluster B1 or B2 (Figure 3C). Here, EGFR is linked to cancer.