Vantiv, an integrated payment processor is expanding its relationship with Discover Financial, to support PayPal in-store checkout at Vantiv's brick-and-mortar merchants over the Discover Payment Services infrastructure (view press release). The companies will work together to ‘open the doors’ of their respective brick-and-mortar merchants to PayPal's estimated 50 million active US account holders and their digital wallet beginning in the second quarter of 2013.