  Investigations of natural variation in cell mechanics within a cell
population are essential to understand the stochastic nature of soft-network
deformation. Striking commonalities have been found concerning the average
values and distribution of rheological parameters of cells: first, attached and
suspended cells exhibit power-law rheological behavior; second, cell stiffness
is distributed log-normally. A predictive connection between these two
near-universal findings has not been reported, to our knowledge. Here we
postulate, based on our own and others' experimental reports and leading models
of cell rheology, that the exponent that characterizes power-law rheology
varies intrinsically among cells as an approximately Gaussian-distributed
variable. Besides explaining naturally the log-normal distribution of cell
stiffness that is widely observed, this postulate predicts multiple empirically
observed relationships from cell deformation studies. Our framework ultimately
links inherent noise in postulated relaxation mechanisms of cytoskeletal
networks to mechanical variation among cells and cell populations.
