Larsson O, Zetterberg A, Engström W
J Cell Sci. 1985 Apr;75:259-68. doi: 10.1242/jcs.75.1.259.
Proliferating serum-dependent 3T3 cells prolong their intermitotic time by 9-10 h after exposure to serum-free medium for only 1 h. This delay was only observed in cells younger than 4 h, i.e. cells in the postmitotic G1 phase (G1pm), as defined by time elapsed since previous mitosis. These data confirm earlier findings that cells are very sensitive to growth factor or serum depletion during the first part of G1 and that only a short exposure to serum-free medium is sufficient for the cells to leave the cell cycle. However, such cells that have delayed their first cell cycle in response to a short exposure to serum-free medium in early G1 exhibit a reduced capacity to delay the subsequent cycle in response to a repeated exposure to serum-free medium. In contrast cells older than 4 h that are exposed for short periods to serum-free medium undergo cell division on schedule, but delay the subsequent cell cycle by several hours. This delay of the progeny cycle is mainly ascribable to the postmitotic part of G1 (G1pm). These data suggest that short exposures to serum-free medium exert an indirect effect on the progeny cell cycle and demonstrate that cycle times are not necessarily determined de novo in the lifetime of every cell, but may be influenced by events in the preceding cycle.
增殖性血清依赖的3T3细胞在仅暴露于无血清培养基1小时后，其分裂间期延长9 - 10小时。这种延迟仅在小于4小时的细胞中观察到，即自上次有丝分裂以来经过的时间所定义的有丝分裂后G1期（G1pm）的细胞。这些数据证实了早期的发现，即细胞在G1期的第一部分对生长因子或血清缺乏非常敏感，并且仅短时间暴露于无血清培养基就足以使细胞离开细胞周期。然而，那些在G1早期因短时间暴露于无血清培养基而延迟其第一个细胞周期的细胞，在再次暴露于无血清培养基时，延迟后续周期的能力降低。相比之下，大于4小时的细胞短时间暴露于无血清培养基后会按时进行细胞分裂，但会将后续细胞周期延迟数小时。子代周期的这种延迟主要归因于G1期的有丝分裂后部分（G1pm）。这些数据表明，短时间暴露于无血清培养基对子代细胞周期产生间接影响，并证明细胞周期时间不一定在每个细胞的生命周期中重新确定，而是可能受到前一个周期中事件的影响。
