FIG. 2.
Reduced levels of p53 and several of its target gene products in XP-E strains. (A) Levels of p53, p21CDKN1A, and p48DDB2 proteins and actin before and 48 h after 12 J of UV irradiation m−2. Samples were prepared, analyzed by Western blotting, and quantitated as described inMaterials and Methods. Each level in the normal IMR-90 strain was designated as 1.0. The chemiluminescence exposure times were 20 s (p53), 30 s (p21CDKN1A), 20 min (p48DDB2), or 10 s (actin). The band marked with an asterisk lying just below p48DDB2 is nonspecific. (B and C) Quantitation of p53 (B) and p21CDKN1A (C) levels before and 48 h after 12 J of UV irradiation m−2. p53 and p21CDKN1A protein levels were normalized to those of actin, and then the level in the unirradiated IMR-90 strain was designated as 1.0. Each value was determined by 6 (IMR-90), 4 (XP3RO), or 3 (Hs27, GM01389, Ops1, and XP2RO) experiments for p53 levels; 10 (Hs27), 8 (IMR-90), 5 (XP2RO), 4 (XP3RO and GM01389), or 3 (Ops1) experiments for p21CDKN1A levels. (D) The basal protein levels of p53, p21CDKN1A, p21BAX, MDM2, p48DDB2, p127DDB1, and actin. The chemiluminescence exposure times were 20 s (p53), 30 s (p21CDKN1A), 5 s (p21BAX), 10 s (MDM2, p127DDB1, and actin), or 20 min (p48DDB2). The band marked with an asterisk lying just below p48DDB2 is nonspecific.