Notched box plot of the weighted mean of the 3′ UTR length shows the translational efficiency difference of mRNAs with different 3′ UTR lengths. For each gene with UTR-APA, the length of each 3′ UTR isoform was normalized to the longest 3′ UTR, and the weighted mean of 3′ UTR length was calculated. P-values were obtained with the linear mixed model and F-test.