RAC1 and breast cancer: In breast cancer 4T1 cells, following lentiviral depletion of V1C1 subunit expression, the actin cytoskeletons lost their regular orientation resulting in decreased migratory and invasive activity, suggesting that V1C1 is able to regulate actin cytoskeleton rearrangements.62 Moreover, V‐ATPase inhibition is associated with F‐actin reorganization in PC‐3 prostate cancer cells.63 In addition, inhibition of V‐ATPase using archazolid A or Voc subunit siRNA in SKBR3 breast cancer cells altered the distribution and localization of EGFR and Rac‐1, which are associated with cellular migration.64