MAPK8 and nonpapillary renal cell carcinoma: IGFBP3 knockdown noticeably reduced the levels of p-AKT, p-STAT3, p-JNK, p-P38, p-ERK and Snail, suggesting that IGFBP3 was indeed the pivotal upstream factor of the AKT/STAT3/MAPK-Snail signalling pathways in ccRCC cells.