At this time, more than ever, remember rule number 1:
=== CRYPTOCURRENCY RULE #1 ===
If you don't control the private keys, you don't own the cryptocurrency. Someone else does, and you're hoping they will give it back later.
Holding cryptocurrency on centralized exchanges defeats the purpose of decentralized, programmable money.
Here's the announcement post from Steemitblog:
Some of my previous posts on the subject: