SMPD3 and cancer: The expression of secretory miR-16 (supplemental Fig. 2A), which is known to abundantly existed in exosome, as well as exosome quantity, as determined by immunoblotting for exosome markers, HSP70 and Alix (supplemental Fig. 2B), protein concentration (supplemental Fig. 2C), and nanoparticle tracking analysis (supplemental Fig. 2D), decreased in nSMase2-knockdown cancer cells (4T1-nSMase2-KD cells) but increased in nSMase2-overexpressing cancer cells (4T1-nSMase2-OE cells).