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. 2020 Oct 28;6:111. doi: 10.1038/s41420-020-00345-4

Fig. 6. MDM2 inhibition causes E2F1 protein downregulation and pRb increase in p53-wt and p53-null cells.

Fig. 6

A Western blot analysis on cell extracts from 2102EP(S) (EPS) and NCCIT cell lines treated for 12 and 24 h with or without 5 μM sempervirine or 5 μM nutlin probed for pRB, E2F1, p53, and MDM2. Clathrin is the reference gene. Arrowheads point to the two bands that correspond to a faster migrating band (unphosphorylated form, pRB) and a slower migrating band (phosphorylated form, p-pRB) of p130 retinoblastoma; n = 3. B Western blot analysis on cell extracts from 2102EP(S) (EPS) cells treated for 24 h with or without 5 μM sempervirine, and probed for E2F1. Tubulin is the reference gene; n = 3. C Schematic representation of sempervirine mechanisms of action: sempervirine binds to nucleolar RNA and affects RPA194 stability, leading to nucleolar stress and MDM2 inhibition. Arrows indicate the concomitant activation of cell death and cell cycle arrest pathways.