The work measures signal transduction components in response to cytokine stimulation including cognate receptors, adjacent kinases, latent transcription factors and target genes on transcriptional, protein and posttranslational level. Mathematical modelling revealed that the signal leading to cell survival is regulated by varying cytoplasmic volumes, a mechanism likely to be conserved in the family of signal transducers and activators of transcription (STATs). The work can be found under: Adlung et al. Cell-to-cell variability in JAK2/STAT5 pathway components and cytoplasmic volumes defines survival threshold in erythroid progenitor cells, Cell Reports (2021).