To interrogate whether the DSE events that were validated in the MCF7 and MDA-MB-231 cell lines could define a breast cancer-associated AS signature in patients, we analyzed The Cancer Genome Atlas (TCGA) SpliceSeq datasets as well as their associated clinical information for COMMD4, GNAS, MATR3, RHOC, MARK3, POLDIP3, FASTK, BAX, and EXOC7. For COMMD4, two alternative isoforms were analyzed (namely COMMD4_AS1 and COMMD4_AS2). This evidence concerns the gene MATR3 and breast carcinoma.