There are two interfaces on which handover signalling messages exchanges either with peer eNodeB (using X2) or MME (using S1).
X2 interface is between two eNodeBs and handover signalling between them always related to intra LTE (intra/inter frequency).
But in the case of S1 interface, handover can be (IntraLTE/ LTEtoUTRAN/ LTEtoGERAN) . If UE is moving from LTE to UMTS , on going bearer related procedure will be aborted and once the UE moves to UMTS, it will initiate new bearer related message.
I am still not sure in case of Inter-RAT handover, I answered based on understanding of the LTE system.
Please correct me if I am wrong in this context.