Fig. 3

Types of alternative splicing alterations. a Classification of alternative splicing (AS) events using SUPPA. A3—Alternative 3′ Splice Site; A5—Alternative 5′ Splice Site; AF—Alternative First Exon; AL—Alternative Last Exon; MX—Mutually Exclusive Exon; RI—Retained Intron; SE—Skipping Exon. b Alternative promoter sites (AF) is the most common type of splicing events detected and most AF events are found in novel isoforms (NIC or NNC). c Alternative splicing events in novel isoforms are expressed at lower level. Novel AF, AL, and MX show relatively higher expression. d Variability of SE event percent spliced in (PSI) observed across SE types. The highest variation is observed in the AF of novel isoforms. e Gene ontology analysis of the top 500 most variable SE events—genes involved in commonly dysregulated pathways in gastric cancer are also target of alternative splicing/promoter (such as cell adhesion and developmental processes). p value has been adjusted for gene length bias. f Heatmap showing the 50 most variable AS events—most of the most variable AS are AF