400nl-river check raise, what now?

[Curryboy]

Hadn't been at the table long so no real read on villain. Doesn't look like a spot for a bluff, opinions?

Hand P4-49473438-114, Started at 09/08/2007 2:21 PM (EDT)
Table 'Akyab': $4-$4 No Limit HE (Real)
Seat 0: Villain ($431.20 in chips)
Seat 2: manikat ($46.80 in chips)
Seat 5: REKTUMZ ($214.50 in chips)
Seat 6: boompe67 ($367.95 in chips)
Seat 7: hissidrekka ($110.50 in chips)
Seat 8: Hero ($457 in chips)
Seat 9: syltunge ($328.35 in chips) (on the button)
*** Blind Bet Round *** :
Villain : Post Blind ($2)
manikat : Post Blind ($4)
Dealt to Hero: Ad
Dealt to Hero: 4d
*** Pre-Flop *** :
REKTUMZ : Fold
boompe67 : Fold
hissidrekka : Fold
Hero : Bet ($16)
syltunge : Fold
Villain : Call ($14)
manikat : Fold
*** Flop *** : Ah 7c 4s
Villain : Check
Hero : Bet ($19)
Villain : Call ($19)
*** Turn *** : [ Ah 7c 4s ] 10d
Villain : Check
Hero : Bet ($36)
Villain : Call ($36)
*** River *** : [ Ah 7c 4s 10d ] 5h
Villain : Check
Hero : Bet ($90)
Villain : Raise ($220)

Hero : ......

[Al_Money]

Looks like a fold, higher two pair or slowplayed set.