Fig. 1

Principal coordinate (classical multi-dimensional scaling) analysis of plasma shotgun proteomics data from two multicenter patient studies a and b numerical labels represent sample run order, higher values predominantly correspond to positive values of the 2nd principal coordinate; color indicates actin beta levels above (pink) and below (cyan) median; principal coordinates scaled to zero mean and unit variance) and correlation of study site average actin beta rank between two batches (c)—letters indicate study sites. In both studies samples with higher levels of intracellular proteins show greater between-sample variability compared to those with lower levels of intracellular proteins