“…Closing these connections by lindane, an inhibitor of gap junction, lead to the inhibition of bystander effect, evidenced as the reduced expression of TP53, CDKN1A (p21) and CDC2 genes (Azzam et al, 1998), or increased survival of clonogens (Bishayee et al, 1999). Several studies have demonstrated that the radiation-induced bystander effect triggers apoptosis (Prise et al, 1998, Morthersill and Seymour, 2001, Przybyszewski et al, 2004 and increase of micronucleus frequency, DNA double-strand breaks (DSBs) measured as histone H2AX phosphorylation (Sokolov et al, 2007, Burdak-Rothkam et al, 2007, accumulation of p53 (Tartier et al, 2007) andATM andATR proteins (Burdak-Rothkam et al, 2008), epigenetic changes, such as DNA hypomethylation, as well as the expression of other genes (Chaudry, 2006, Iwakawa et al, 2008, Rzeszowska-Wolny et al, 2009b. Many of these experiments showed that higher doses of radiation, including those used in conventional radiotherapy, also induce bystander effects in non-irradiated cells.…”