Cell stage–specific expression at lncRNA and protein-coding loci. Principal component analysis of regularized log-transformed expression patterns at (A) protein-coding loci and (B) the 4516 lncRNA loci identified in this study. Dashed gray lines indicate groups identified by unsupervised hierarchical clustering (Supplemental Figure 7A-B). (C) Box plots of specificity of expression of all coding and lncRNA loci separated into quartile bins on the basis of their median expression across all 8 B-cell stages. Numbers below each quartile indicate the number of lncRNA and protein-coding loci that fall into each category. Venn diagrams showing the number of protein-coding (D) and lncRNA (E) loci that are either expressed in multiple cell populations (blue) or expressed in a single cell population (red) at an FPKM threshold of 1.0. Splenic plasmablasts (PB) and plasma cells (PC (SP)), and bone marrow plasma cells (PC (BM)). Numbers adjacent to each plot depict the proportion of loci falling into each category.