  Cell growth in size is a complex process coordinated by intrinsic and
environmental signals. In a recent work [Tzur et al., Science, 2009,
325:167-171], size distributions in an exponentially growing population of
mammalian cells were used to infer the growth rate in size. The results suggest
that cell growth is neither linear nor exponential, but subject to
size-dependent regulation. To explain their data, we build a model in which the
cell growth rate is controlled by the relative amount of mRNA and ribosomes in
a cell. Plus a stochastic division rule, the evolutionary process of a
population of cells can be simulated and the statistics of the in-silico
population agree well with the experimental data. To further explore the model
space, alternative growth models and division rules are studied. This work may
serve as a starting point for us to understand the rational behind cell growth
and size regulation using predictive models.
