FGFR3 and breast cancer: On the other side—and complementary to findings from whole-genome sequencing—RNA-sequencing identified at least 4 transcriptomic subtypes; among them, the attention was focused on Cluster 1 (Papillary-like), which is characterized by FGFR3 gene aberrations (mutations, amplifications, rearrangements), potentially targetable with FGFR3 inhibitors, and Cluster 3 (basal/squamouslike), similar to basal-like breast cancers.