Cell Cycle Proteins/metabolism; DNA Damage/physiology; DNA-Binding Proteins/metabolism; Phosphoprotein Phosphatases/metabolism; Protein Serine-Threonine Kinases/metabolism; Proto-Oncogene Proteins c-mdm2/metabolism; Tumor Suppressor Protein p53/metabolism; Tumor Suppressor Proteins/metabolism; Ubiquitin Thiolesterase/metabolism; Amino Acid Sequence; Ataxia Telangiectasia Mutated Proteins; Casein Kinase II/genetics; Casein Kinase II/metabolism; Cell Cycle Checkpoints; Cell Cycle Proteins/genetics; DNA-Binding Proteins/genetics; Down-Regulation; HeLa Cells/radiation effects; Humans; Molecular Sequence Data; Phosphoprotein Phosphatases/genetics; Phosphorylation; Protein Phosphatase 2C; Protein Serine-Threonine Kinases/genetics; Proto-Oncogene Proteins c-mdm2/genetics; Radiation, Ionizing; Serine/metabolism; Signal Transduction; Tumor Suppressor Protein p53/genetics; Tumor Suppressor Proteins/genetics; Ubiquitin Thiolesterase/genetics; Ubiquitin-Specific Peptidase 7