In tomato rootstock and Nicotiana benthamiana heterografting systems, N. benthamiana scions show stress and defense-related transcripts derived from tomato rootstock. tRNA-like and poly-pyrimidine sequences in mRNA untranslated regions (UTRs) may facilitate mRNA mobility. To understand UTR contributions, two transgenes were created using tomato major latex protein (MLP) and green fluorescent protein (GFP) open reading frames (ORFs) flanked by previously identified mobile mRNA UTRs. Agroinfiltration into N. benthamiana was performed to study mRNA mobility and protein expression. Preliminary results show MLP mRNA is mobile, supporting its role in mRNA mobility. Ongoing research is investigating the mobility and protein expression of both GFP and MLP mRNAs to develop new mRNA expression cassettes capable of moving systemically and expressing proteins of desired functions.