biostudies-literatureUnknown102(5)Shu SBlebbistatin, a cell-permeable inhibitor of class-II myosins, was developed to provide a tool for studying the biologic roles of myosin II. Consistent with this use, we find that blebbistatin inhibits three myosin II-dependent processes in Dictyostelium (growth in suspension culture, capping of Con A receptors, and development to fruiting bodies) and does not inhibit growth on plates, which does not require myosin II. As expected, macropinocytosis (myosin I-dependent), contractile vacuole activity (myosin V-dependent), and phagocytosis (myosin VII-dependent), none of which requires myosin II, are not inhibited by blebbistatin in myosin II-null cells, but, unexpectedly, blebbistatin does inhibit macropinocytosis and phagocytosis by cells expressing myosin II. Expression of catalytically inaProceedings of the National Academy of Sciences of the United States of America1472-7https://www.ebi.ac.uk/biostudies/studies/S-EPMC547870biostudies-literatureBlebbistatin and blebbistatin-inactivated myosin II inhibit myosin II-independent processes in Dictyostelium.PMC547870Liu XShu SKorn EDfalseBlebbistatin and blebbistatin-inactivated myosin II inhibit myosin II-independent processes in Dictyostelium.Blebbistatin, a cell-permeable inhibitor of class-II myosins, was developed to provide a tool for studying the biologic roles of myosin II. Consistent with this use, we find that blebbistatin inhibits three myosin II-dependent processes in Dictyostelium (growth in suspension culture, capping of Con A receptors, and development to fruiting bodies) and does not inhibit growth on plates, which does not require myosin II. As expected, macropinocytosis (myosin I-dependent), contractile vacuole activity (myosin V-dependent), and phagocytosis (myosin VII-dependent), none of which requires myosin II, are not inhibited by blebbistatin in myosin II-null cells, but, unexpectedly, blebbistatin does inhibit macropinocytosis and phagocytosis by cells expressing myosin II. Expression of catalytically ina2005-01-01T00:00:00Z2005 Feb2026-07-15T07:05:34.699Z2019-03-27T01:08:34ZS-EPMC5478701567118210.1073/pnas.0409528102