RAB27B and urinary bladder cancer: Evidence indicated that knockdown of Rab27a or Rab27b by RNAi inhibited the secretion of exosomes from a variety of tumor cells, such as cervical cancer cells76, bladder cancer cells77, HNSCCs93,95, etc. The downregulation of Rab27a or Rab27b blocked the transport of MVB to the cell periphery as well as the docking to the cell membrane, resulting in TDE inhibition76.