Loss of p16 INK4a Uncouples the Centrosome Duplication and DNA Replication Cycles in HMECs (A) Western blot analysis of p16 INK4a expression in HMECs parental, infected with vector-only (vector), or shRNA directed against p16 INK4a (p16 INK4a shRNA). (B, arrowhead) Examples of more than two centrosomes in HU-exposed HMECs (p16 INK4a shRNA). (C) HMECs infected with vector-only (black: RM9 [6 and 7 PD]) or p16 INK4a shRNA (gray: RM9 [7 and 8 PD]) were untreated (−HU) or exposed to HU (+HU). (D) Expression levels of p16 INK4a (red) in HMECs, vHMECs transfected with vector-only or p16 INK4a . (E) vHMECs infected with vector-only (red: RM15 [33 to 37 PD]) or p16 INK4a (gray: RM15 [33 to 37 PD]) were untreated (−HU) or exposed to HU (+HU). Centrosome number was determined by immunocytochemistry with an antibody recognizing the centrosome-associated γ-tubulin protein. Analysis included at least 100 cells. *Statistical significance ( p
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