Thanks, I felt confused at this point, the following is from MIT

When Form I-485 is Filed Separately from the Form I-140: If Form I-140 is already pending or approved, the I-485 package for the principal and accompanying dependents should be mailed to the Service Center where the I-140 was sent (as specified on the Form I-140 Receipt Notice, or on a subsequent transfer notice, if the case was transferred). That will be either the Nebraska Service Center or the Texas Service Center. Include a copy of the USCIS I-140 receipt notice or approval notice, and transfer notice.