MSR1 and nonpapillary renal cell carcinoma: Macrophages expressed high levels of CD64 (FCGR1A) (Figure 4a); a weak correlation between CD64 (FCGR1A) and CD204 (MSR1), a macrophage marker, was detected in ccRCC tissues (Spearman's R = 0.157, P < 0.01) (Figure 4a).