CD81 and neoplasm: We compared mass spectrometry proteomic profiling of clustering and non-clustering TNBC patient-derived xenografts (PDXs) tumor cells and identified CD81, a tetraspanin protein enriched in extracellular vesicles (EVs) (Kowal et al., 2016; Mathieu et al., 2021), as one of the altered proteins upon CD44 depletion.