GGTI298 is a CAAZ peptidomimetic geranylgeranyltransferase I (GGTase I) inhibitor, strongly inhibiting the processing of geranylgeranylated Rap1A with little effect on processing of farnesylated Ha-Ras, with IC₅₀ values of 3 and > 20 μM in vivo, respectively. IC50 & Target: IC50: 3 μM (Rap1A, in vivo), > 20 μM (Ha-Ras, in vivo)^[3] In Vitro: Both RhoA inhibitor (GGTI298) and ROCK inhibitor (H1152) significantly reduce cAMP agonist-stimulated IK(ap), whereas the latter additionally reduces colocalization of KCNN4c with the apical membrane marker wheat germ agglutinin in T84WT cells^[1]. Knockdown of DR4 abolishes NF-κB activation, leading to sensitization of DR5-dependent apoptosis induced by the combination of GGTI298 and TRAIL. GGTI298/TRAIL activates NF-κB and inhibits Akt. knockdown of DR5, preventes GGTI298/TRAIL-induced IκBα and p-Akt reduction, suggesting that DR5 mediates reduction of IκBα and p-Akt induced by GGTI298/TRAIL. In contrast, DR4 knockdown further facilitates GGTI298/TRAIL-induced p-Akt reduction^[2]. In Vivo: The vivo mouse ileal loop experiments show fluid accumulation is reduced in a dose-dependent manner by TRAM-34, GGTI298, or H1152 when injected together with cholera toxin into the loop^[1].