PIWIL4 and cancer: Interestingly, ASPM was found in EV derived from serum, urine, and different types of cancer cells (Sarker et al., 2014); FANCD2 in EV of serum, urine and CRC cells (Hong et al., 2009; Fraser et al., 2013); and PIWIL4 (a canonical RBP) was also found in serum, urine and CRC cells (Hong et al., 2009; Musante et al., 2012; Fraser et al., 2013).