FBXW7β transcript is protein-coding and is enriched in the heavy polysome fraction. (A) Analysis of FBXW7 AFE usage based on short-read RNA-Seq in REH. (B) ONT long-read RNA sequencing demonstrates full-length FBXW7β transcript expression in REH. (C) Detection of FBXW7 protein isoforms following robust transient overexpression in 293T cells using anti-FLAG IP and immunoblotting. (D) DDA MS allowing detection of overexpressed FBXW7 isoform-specific peptides in 293T cells, in addition to peptide sequences common to all isoforms. (E) Polysome profiling followed by qPCR. Specific mRNA distribution was expressed as a percentage of the total signal.