*2.1. Chemicals*

N-4-hydroxyphenyl-retinamide (fenretinide, 4-HPR) was purchased from Olon Spa (Milan, Italy); spermidine, soy L-α-phosphatidylcholine, glyceryl tributyrate, 2-hydroxypropyl beta cyclodextrin (Mw 1460), and KOH from Sigma-Aldrich (Milan, Italy); ethanol absolute anhydrous from Carlo Erba Reagents (Milan, Italy). DMEM medium, dichlorofluorescein diacetate (DCHFDA), Hoechst 33342, glutamine, trypsine/EDTA solutions, and Human Serum were from Sigma-Aldrich.
