Figure 1.

(A) Western blot analysis of p53 and p21^Waf1 expression levels in low fluence α-particle exposed normal human fibroblasts. Confluent density-inhibited AG1522 skin or HLF-1 lung fibroblasts were exposed to α-particles doses ranging from 0.16 to 85 cGy and held at 37°C for 3 h. Cell lysates from irradiated and control nonexposed cultures were prepared and examined. (B) In situ immunofluorescence detection of p21^Waf1 in control and α-particle exposed (0.3 cGy) AG1522 density-inhibited cultures where induction is seen to occur in aggregates of cells. About 1 cell in 50 would be traversed by an α-particle at this mean dose.