Stochastic simulations indicating all-or-none, but heterogeneous responses in individual B cells using Blimp-1 and Pax5 as dual expression markers. The B cell population (1000 cells) splits into two distinct clusters under continuous LPS stimulation for 72 h - the cluster with low Blimp-1/high Pax5 represents B cells, while the cluster with high Blimp-1/low Pax5 represents plasma cells. Individual B cells switch to the plasma cell state randomly over time and higher LPS concentration results in more plasma cells. Top panels: 1 μg/ml LPS, bottom panels: 10 μg/ml LPS. Note: to help visualize cells with zero copy number of Blimp-1 or Pax5 proteins on logarithmic scale, a number drawn randomly from a log-normal distribution (with mean = 1 and variance = 0.1) was added to the simulated protein expression data. This in effect mimics background fluorescence in flow cytometry studies measuring protein expression.