Cluster 2 ECs may be involved in extracellular matrix (ECM) remodeling in ccRCC, as evidenced by the high expression of ECM protein-coding genes (COL4A1, COL4A2, HSPG2, and ITGA6) in this subgroup (Figure 6C). The gene discussed is HSPG2; the disease is nonpapillary renal cell carcinoma.