Cells make decisions by communicating with other cells and receiving signals from their environment. Computational tools have been developed to infer cell–cell communication through ligands and receptors using single-cell transcriptomics. However, current methods focus only on signals sent by the measured cells, overlooking received signals from the external system. In this talk, exFINDER, a computational approach identifying external signals received by cells in single-cell transcriptomics datasets, will be introduced. Then we will delve into the analysis of associated ligand-target signaling networks. Furthermore, we will discuss the potential integration of computational methods and deterministic models for inferring cell lineages.