Fig 1. Functional enrichment among genes with different expression level and noise.

A, Left panel: Unsupervised hierarchical clustering of the single-cell transcriptomes of 20 cells. 7741 genes with at least one sequencing read detected in all 20 cells were used for the analysis. Right panel: The formulae used to calculate expression level (μ) and noise (CV). B, Left panel: Expression noise is negatively correlated with expression level in human embryonic cells (r = -0.66, P < 1×10⁻¹⁰⁰, N = 7741, Pearson’s correlation). Genes were further divided into 4 groups by the major axis and minor axis. Grey line indicates the estimated technical noise under given expression levels. Right panel: Enriched KEGG pathways in each group of genes.