A cell on its way to becoming skin pigment, blood, or nerve does not make that shift alone. It responds to a dense web of molecular instructions, some pushing forward, others holding it back. Biologists have gotten much better at tracing where cells are headed. Pinning down which regulators actually steer those choices has been much tougher. That is the problem a new model called RegVelo set out to solve. Published in bioRxiv, the framework combines two areas of single-cell biology that have often been treated separately: tracking how cells move through development, and mapping the gene regulatory networks that shape that movement. Instead of only estimating a cell’s likely direction of change, RegVelo also tries to identify the underlying interactions among genes that drive that change. “For a long time, cellular dynamics and gene regulation have largely been modeled separately,” said Prof. Fabian J. Theis, co-senior author of the study, director of the Computational Health Center at Helmholtz Munich, and professor at the Technical University of Munich. “RegVelo brings those pieces together, allowing us …