Fig. 3. Growth kinetics of ef-2^OE, ef-2^AS, ef2-null and parental Ax-2 cells. The four kinds of cells were separately shaken in growth medium without G418- or blasticidin S-addition at 22.0°C at 150 rpm. The number of cells at the exponential growth phase was determined using a hemocytometer. Similar results were obtained by cell counts in three independent experiments (, Ax-2; , ef-2^OE; , ef-2^AS; , ef2-null).