Differentiating Cells in Culture (IMAGE) California Institute of Technology Caption These are images of B cells (left, red arrowheads), progenitor cells (center, black arrowhead), and macrophages (right, blue arrowhead) taken from a time-lapse movie of differentiating cells in culture. The brightness of green indicates the amount of the regulatory protein PU.1 present. Credit Hao Yuan Kueh, Michael Elowitz and Ellen Rothenberg/Caltech Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.