Although knockdown of RAB27B showed no common alterations of the expression pattern of VEGF- or MAPK-related proteins in the western blot analyses, Erk1/2 or p38 MAPK protein was faintly decreased in 786-O, A498, or SU-R-786-O after si-RAB27B transfection (S5 Fig), suggesting that RAB27B might partially contributed to accelerating MAPK pathway in RCC. Here, MAPK3 is linked to renal cell carcinoma.