Can I fold bottom set, NL25?

[Nichlemn]

PokerStars No-Limit Hold'em, $0.25 BB (9 handed) Poker Stars Converter Tool from FlopTurnRiver.com (Format: 2+2 Forums)

MP1 ($14.15)
MP2 ($39.95)
MP3 ($33.95)
Hero ($28.25)
Button ($3.40)
SB ($24.75)
BB ($25)
UTG ($4.40)
UTG+1 ($20.85)

Preflop: Hero is CO with 2[img]/images/graemlins/club.gif[/img], 2[img]/images/graemlins/diamond.gif[/img].
<font color="#666666">1 fold</font>, <font color="#CC3333">UTG+1 raises to $0.75</font>, <font color="#666666">2 folds</font>, <font color="#CC3333">MP3 raises to $1.5</font>, Hero calls $1.50, <font color="#666666">2 folds</font>, BB calls $1.25, UTG+1 calls $0.75.

Flop: ($6.10) 2[img]/images/graemlins/heart.gif[/img], 8[img]/images/graemlins/club.gif[/img], 9[img]/images/graemlins/diamond.gif[/img] <font color="#0000FF">(4 players)</font>
<font color="#CC3333">BB bets $2</font>, UTG+1 folds, MP3 folds, <font color="#CC3333">Hero raises to $7</font>, <font color="#CC3333">BB raises to $23.5</font>, Hero ???

What exactly can we put BB on here, smooth calling a 3 bet preflop? TT? JJ? The line seems to an even better fit for a set miner. If he'd been the preflop aggressor, it'd have been all fine, but this seems to be a bit trickier. I think as long as he can do this a fraction of the time with TT or JJ, it's a good call, but by no means a fist pump I think...


On a slightly related note, how much equity do you think I need to call 4-bet shoves from unknowns at NL25 with QQ? I think it's safe to assume they're usually KK+, but wondering what degree it is AK, JJ and other random stuff to make it worthwhile? I'm getting into situations like 1.67:1 (needing 37.5% equity). It's +EV if they're shoving with JJ or AK a bit less than half the time, but I'm not sure what a good approximation is.