PayPal PayFlow Pro supports the following processors:
 
American Express Phoenix
EDS Aurora
FDMS Nashville
FDMS North
FDMS South
FDRA
Global Payments Central 
Global Payments East
Merchant e-Solutions
Norwest
Nova
Paymentech New Hampshire
Paymentech Tampa
TSYS (Vital)
Unspecified
Wells Fargo
*NOTE- List subject to change by PayPal