TAT and neoplasm: Additionally, In vivo distribution studies showed that Tat-A1E28 and Tat-A4V48 delivered Cy5.5 labeled siRNA specifically into tumor tissues in 4T1-allograft murine model, whereas free siRNA and Tat-E28 mediated delivery resulted in minimal accumulation in tumor tissues and strong non-specific accumulation (Additional file 9: Figure S9).