Exogenous Tβ4 can function like a hormone on cells in terms of its ability to modulate their biological behavior. Since one of the primary roles of Tβ4 in cells is the sequestration of actin monomers, and the protein is not secreted, previously indicated that it was unlikely that Tβ4 could have a hormonal function . However, other studies have shown that the intracellular level of Tβ4 or its mRNA can be significantly and rapidly altered by external stimuli and that change in the level of Tβ4 often are correlated with cell differentiation [18, 43]. In the present study, exogenous Tβ4 peptide activate intracellular Tβ4, which results suggested that exogenous Tβ4 spontaneously enter the cytoplasm through rapid internalization, and acts their functions same as endogenous one [8, 18].
5-HTP is sold over the counter in the United States, Canada, the Netherlands, and the United Kingdom as a dietary supplement for use as an antidepressant, appetite suppressant, and sleep aid. It is also marketed in many European countries for the indication of major depression under the trade names Cincofarm, Levothym, Levotonine, Oxyfan, Telesol, Tript-OH, and Triptum.