tl;dr- It's ManBearPig from South Park. In the future, you can look up stuff like this with a reverse image search, like this one.
If you find a strange indicator on a lab door, it may be easiest to do a reverse image search. It's sorta like Google'ing something, just you're querying with an image rather than words.
In this case, I tried TinEye, searching with the image you provided in the question,
by referring to its URL,
https://i.stack.imgur.com/usUNw.png. The search results page reveals that this is a warning about the infamous ManBearPig, as previously documented in the series South Park.
Obviously, this serves as not just a warning about the horrors of the existing monster, but to remind researchers about the potential hazards of their reckless tinkering in what man was not meant to meddle with.