"Step Up" movies..

Are these 3 movies related to each other (or sequels)?
Step Up (2006)
Step Up 2: The Streets (2008)
Step Up 3D (2010)

I can see from IMDB that the cast is different for each movie.

I have seen 'Step Up (2006)' and liked the film atleast for Jenna Dewan-Tatum ; Now I am planning to see Step Up 3D.. Will i miss something if i skip the second movie? And which among these movies do you think is the best?

Thanks in advance!

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SJ.
Wait and Hope

Yes, they all have Step Up in the title and they all have dancing in them. Unfortunately there's going to be another one though.

they are all kind off related each one has some of the old cast in. and u see one grow up from 1st to 3rd film.