MKI67 and renal cell carcinoma: SMA: Smooth muscle actin; HMB: Human melanoma black; CD: Cluster of differentiation; Bcl-2: B-cell lymphoma 2; CK: Cytokeratins; STAT6: Signal transducer and activator of transcription 6; EMA: Epithelial membrane antigen; Ki-67: Kiel-67 (proliferation index); MSA: Muscle specific actin, RCC: Renal cell carcinoma; PAX8: Paired box gene 8; WT1: Wilms tumor 1 protein; S100: Soluble 100 protein