E2F1 and familial pancreatic carcinoma: Another study showed that using gambogic acid to reduce the expression of RRM2 could improve the efficacy of gemcitabine in pancreatic cancer; gambogic acid caused pancreatic cancer cells to become sensitive to gemcitabine in vitro and in vivo by inhibiting the activation of the ERK/E2F1/RRM2 signaling pathway [28].