Introduction Endosomal RHO proteins RHOB and RHOD have recently implicated in receptor and vesicular trafficking in uterine smooth muscle tissues. RHOB and RHOD bind to mammalian diaphanous protein DIAPH1 in late endosomes to regulate vesicular trafficking. DIAPH1 expression is elevated in labour.

Aims and methods Immunoblotting and immunohistochemistry were used to determine the expression and localisation of RHOB and RHOD in freshly harvested human myometrial, placental, chorion and decidual tissue samples. RHOGDI, tubulin and β-actin were used as loading controls.

Results RHOB and RHOD were expressed in the paired myometrial, placental and decidual tissue samples analysed. RHOB protein expression was significantly higher in all placental samples compared to myometrial samples (p<0.01, ANOVA). There were no significant differences in RHOD expression in myometrial and placental samples (p>0.05, ANOVA). RHO protein expression was invariant in the chorio-decidual tissues analysed. Further research is required to elucidate the function of RHO proteins during pregnancy.