TABLE 3.

Immunohistochemical Expression in Clear Cell and Nonclear-cell Sarcomatoid RCC (n=28)

	Staining Grade
	Clear-cell RCC (n=24), No. (%)				Nonclear-cell RCC (n=4), No. (%)
Antibody	0	1	2	3	0	1	2	3
CA9	2 (8)	1 (4)	1 (4)	20 (83)	4 (100)	0 (0)	0 (0)	0 (0)
HIF-1α	6 (25)	3 (13)	4 (17)	11 (46)	4 (100)	0 (0)	0 (0)	0 (0)
p-4E BP1*	8 (35)	2 (9)	3 (13)	10 (43)	4 (100)	0 (0)	0 (0)	0 (0)
p-S6*	4 (18)	2 (9)	3 (9)	14 (61)	2 (50)	2 (50)	0 (0)	0 (0)

^*Staining not analyzed in 1 of 24 clear-cell tumors.

CA9 indicates carbonic anhydrase IX; HIF-1α, hypoxia-inducible factor-1α; p-4E BP1, phosphorylated eukaryotic initiation factor 4E-binding protein 1; pS6, phosphorylated protein S6 kinase 1; RCC, renal cell carcinoma.