Loss of HECT domain results in a reduction in B-cell development proteins and an enrichment in proteins regulating mRNA splicing. (A) Schematic of sample preparation of spleens for TMT MS analysis (N = 3). (B) Quantification of identified peptides and proteins. (C) PCA using components 1 and 2 showing clustering of WT and ΔHECT samples for significantly upregulated proteins. (D) Pie chart of localizations for all 2797 proteins identified by mass spectometry. (E) Volcano plot of the log₂ fold change ΔHECT/WT showing proteins significantly (P < .05) up- (≥1.3) and downregulated (≤0.7). (F) Heatmap of the significantly up- and downregulated proteins showing the top 10 upregulated and top 10 downregulated proteins. (G) Gene ontology analysis showing pathways known to be associated with significantly up- and downregulated proteins using DAVID 6.8 software. For upregulated proteins, includes pathways with ≥10 proteins associated and a P value ≤ .01. Downregulated proteins pathways with P value ≤ .05.