How to use assertions in soapUI to match with external property

I have a test case containing the test steps below :

• (JDBC) LoadTestDataStep
• (Transfer) GetPropertyStep
• (SOAP) SoapRequestStep

In the LoadTestDataStep i load some data from a JDBC database that i will need later in the 'SoapRequestStep'

The GetPropertyStep allow me to retrieve data from LoadTestDataStep result and put them SoapRequestStep request.

Now in the SoapRequestStep i want to assert that an evaluation of some xpath matches some data i retrieve in the LoadTestDataStep

I hope i made myself understandable.