Answer: I'm tempted just to say,

Nope.

But to continue. IV-ii is not really a cadence, it's just a change of harmony. A cadence is a chord change that can mark the end of a musical phrase. You've got your cadences from V to the tonic or tonic substitute like vi, and you have the reverse, the half-cadence. And you have the deceptive cadence, which in theory could go from V to anything unexpected but generally goes to vi, a tonic substitute. And you have the plagal cadence IV-I, root movement by a descending fourth to the tonic.

But ii shares no tones with the tonic and cannot be a tonic substitute even if the first chord were V. As a cadence, IV-ii just doesn't cut the mustard.

Followup question from G.P.:

I was just confused a little bit, and my head was hurting.What else can be considered a plagal cadence instead of IV-I?

Extra-credit reply from J.E.:

Really, that's all there is. The only thing that truly deserves to be called a plagal cadence is IV-I or its minor version, iv-i.

Though it is true that "some theorists" have widened the definition of "plagal cadence" to include ii-i. I don't see the sense of this, except that ii could be seen as a substitute for IV - two of its three pitches are also in the IV chord. So maybe you could see that as being similar to IV-I. But the tonic has to be the end point either way. Were I in charge, which unfortunately it seems I am not, I'd prefer to give a different name to ii-i.

More followup!That is good to know Jeff. My professor has started confusing me in my form and analysis class because he doesn't believe in the Deceptive Cadence. He calls it "Deceptive Motion," and states it is not a cadence. What are your thoughts on the subject?

And the final word:

I'm all in favor of professors who think for themselves, so if I had a hat I'd remove it for your professor. Were I talking about it with him over a beer I might propose that maybe a "cadence" is any kind of harmonic change that clearly punctuates a phrase ending. I wouldn't see every V-vi movement as a cadence, certainly - but then not every V-I is a cadence either. So I'd argue that if the movement has a cadential function, it's a cadence.

The nice thing about such discussions is that they are not likely to become very heated.