CD44 and melanoma: Based on siRNA-mediated knockdown, it has been shown that PTBP1, RBP recognizing CUCUCU-rich sequences (Oberstrass et al., 2005), induced a significant decrease in expression of CD44 containing exon v6 at mRNA and protein level in two melanoma brain metastases’ cell lines BD and M16 (Marzese et al., 2015).