RARB and malignant peripheral nerve sheath tumor: In conclusion, combined treatment of ATRA and MEKi induced expression of bona fide targets of ATRA mediated signaling such as CRABP2, CYP21A1, and RARB. The combination of ATRA and MEKi U0126 or PD0325901 provokes additive effects on reduced viability of T265 and S462 cells, suggesting a new and potentially successful therapeutic option for MPNST.