Figure 5.

Schematic representation of the RIANS model in cells from Category 2 and 3 cancer syndromes. (A). Category 2: Mutated genes are involved in cell cycle checkpoint control. The encoded proteins are X-proteins. The RIANS is delayed by the high cytoplasmic expression of X-proteins, and few ATM monomers enter into the nucleus. Consequently, few DSB are recognized by NHEJ and therefore may be misrepaired. (B). Category 3: Mutated genes are directly involved either in DNA damage recognition and repair or in the cell cycle checkpoint control. The encoded proteins are X-proteins. The RIANS is therefore delayed by the cytoplasmic overexpression of X-proteins, and few ATM monomers may enter into the nucleus. Consequently, few DSB are recognized by NHEJ and therefore may be misrepaired. Furthermore, CHK proteins are not phosphorylated, and therefore, G1/G2 arrests are impaired.