To investigate the effect of REP1 on macropinocytosis, we performed fluorescence microscopy analysis to monitor the intracellular uptake of dextran as a marker of macropinocytosis in the presence or absence of REP1.Unexpectedly, REP1-depleted cells revealed substantially increasing levels of macro pinocytosis in MiaPaCa2 pancreatic cancer cells. Here, CHM is linked to familial pancreatic carcinoma.