Figure 4.

NOTCH1 expression in G₂ DNA damage arrest. A–C, HaCaT cells were left untreated (diagram 1) or treated with hydroxyurea (HU) for 19 h (A). Alternatively, cells were released from the hydroxyurea block and either untreated or treated after 7 h with doxorubicin (DOX) for 1 h and subsequently grown in the presence of nocodazole (NOC) for 18 h. Following these treatments, cells were collected at the indicated time points after release from G₁/S, cell cycle was analyzed by FACS (FACS profile is shown only for HaCaT cells), and cell lysates were immunoblotted with antibodies against the indicated proteins (B and C). Shown are representative results from at least three independent experiments.