HOXA9 and nonpapillary renal cell carcinoma: Of the eight HOX genes (HOXB1, HOXA7, HOXB5, HOXD8, HOXD9, HOXB9, HOXA9, and HOXA11) comprised in our signature, their transcript levels were consistently lower in ccRCC tissues compared to adjacent normal tissues (except for HOXD9).