After the company reported encouraging early-stage trial data for its cystic fibrosis therapies, shares in Proteostasis Therapeutics (NASDAQ: PTI) skyrocketed yesterday, before retreating 23.2% on Friday. Proteostasis didn't issue any press releases today, so it's likely that the sell-off in its shares was because of investors paring back their positions following its massive move on Thursday.IMAGE SOURCE: GETTY IMAGES.Continue reading