RAB27B and neoplasm: Interestingly, after knocking down PKM2 in A549 cells, we failed to find significant alteration in the levels of Rab27a, Rab27b and nSMase2 (Supplementary Fig. 7), suggesting that PKM2's enhancement of exosome secretion in tumour cells is not mediated through changes in the expression of Rab27a, Rab27b and nSMase2.