FIG. 2.

Northern blot analysis of cyclin E2 and cyclin E1 in human lung and cervical epithelial cells. (A) RNAs isolated from normal bronchial epithelial cells (Normal), NSCLC cell lines H1299, H23, H358, H441, H460, H520, H522, and H727, and SCLC cell lines H146, H209, H446, H510A, H526, and H889 were electrophoresed, transferred, and hybridized with probes for cyclin E1 and cyclin E2. 36B4 was included as an internal control for loading efficiency. (B) Western blot analysis of Rb in the same panel of lung cancer cells as used for panel A. Total protein extracts (50 μg) from exponentially growing cells was electrophoresed, transferred, and subsequently probed with antibodies against Rb. The blots were also probed with actin antibody as an internal control for loading efficiency. (C) RNAs isolated from normal cervical epithelial cells (Normal), immortalized cervical epithelial cells expressing the HPV E6 and E7 genes (Immortal), and the cervical cancer cells Caski, C-4-I, MS751, SiHa, and C-33-A were prepared and treated as described for panel A. (D) Total protein extracts (50 μg) from the cervical cells used for panel C were examined for Rb and actin expression as described for panel B. (E) RNA isolated from proliferating primary Rb^+/+ MEFs and Rb^−/− MEFs was electrophoresed, transferred, and hybridized with a probe specific for murine cyclin E2. 36B4 was included as an internal control for loading efficiency.