To determine if CPE mRNA and its splice variant, CPE-∆N (which encodes a 40 kDa protein), are present within exosomes derived from three different cancer cell lines, we used a specific primer set ∆F/∆R which flanks the region of deletion in exon1 to differentiate CPE-∆N mRNA sequence, in addition to primers flanking the rest of the CPE mRNA. Here, CPE is linked to cancer.