FIG. 7.

Northern blot analysis of SRb-7 and Sp53-3 cells carrying the tetracycline-inducible Rb and p53 expression plasmids. SRb-7 (A) or Sp53-3 (B) cells were cultured in the presence or absence of 1 μg of tetracycline (Tc) per ml at 37°C for 6 or 12 h, respectively, poly(A)⁺ RNA was extracted, and Northern blot analysis was performed with a ³²P-radiolabeled probe prepared from the C-terminal region, which includes the 3′ untranslated region of the WRN gene. The relative intensities of individual WRN mRNA bands were estimated with a BAS-1500 Bioimaging Analyzer (Fujifilm).