[Dependence of 3T6 cell proliferation on the serum concentration in the medium]

The characteristics of 3T6 cells in various growth phases and their reaction to the serum content decrease was studied using flow cytofluorimetry, autoradiography and thymidine incorporation in acid-insoluble cell fraction. It is concluded that 3T6 cells are arrested in G1 period after reaching the confluent state, or when the serum concentration in the cultural medium is below 0.5%. The "quiescence" state of 3T6 cells cannot be identified with Go state. The variable data seen in the case of the culture transfer into the medium with decreased serum content may suggest the necessity to control the arrest of cell proliferation in each case examined.