Eminem and D12 didn't make a song called hit em up.
And if you care to point me to a track on any Eminem or D12 album with a "remake" of a 2pac song on it, i'll eat my laptop.
As for mixtape stuff... Isn't that the point, to put your lyrics over someone elses beat.
All Aftermath haters... I'm waiting.
And as for Nas, he didn't remake / bite a 2pac song, he used the same sample, it's been done many many times, it's common place in hip-hop.
Hang on what about hit em up, was that a remake of a Biggy / Junior Mafia song?