HIF1A and nonpapillary renal cell carcinoma: Determination of HIF-1α only, HIF-2α only, and co-expression of HIF-1α & HIF-2α revealed that the incidence of HIF-1α only was high (20%) in head & neck cancer compared to colon (11%) and ccRCC (9%), whereas HIF-2α only incidence was low in head & neck (17%) and colon (16%) cancers compared to ccRCC (47%).