Figure 4.

Conditional expression of KRAS(G12V) in the colorectal carcinoma cell line Caco2 induces YB-1 phosphorylation in the nucleus by stimulating RSK nuclear translocation. (A) Cells were treated with doxycycline (2 µg/mL) for the indicated times and mock irradiated or irradiated (4 Gy). Cytoplasmic and nuclear fractions were prepared 30 min after irradiation. (B) KRAS(G12V) was conditionally induced after treatment with doxycycline for 48 h. Treatment with the RSK inhibitor LJI308 (5 µM, 24 h) was performed followed by cytoplasmic and nuclear protein preparation. KRAS, P-YB-1, YB-1, P-ATM, ATM, and RSK1/2/3 levels were assessed via Western blotting. α-Tubulin and lamin A/C were detected as cytoplasmic and nuclear markers. Arrows indicate distinct RSK isoforms.