These findings suggested that Rab7a is an “effector” of TPC2 but not vice versa (with “effector” being defined here as an upstream molecule (Rab7a) interacting with a downstream target (TPC2) to increase its activity) and that effects of Rab7a on proliferation, migration, and invasion of tumor cells are mediated predominantly by TPC2. Here, TPCN2 is linked to neoplasm.