0 -> MrnaP21 P53 -> MrnaP21 + P53 0 -> MrnaCy 0 -> MrnaP53 MrnaP21 -> 0 MrnaCy -> 0 MrnaP53 -> 0 MrnaP21 -> MrnaP21 + P21 P21 -> 0 MrnaCy -> Cy + MrnaCy Cy -> 0 Cy + P21 -> CyP21 CyP21 -> Cy + P21 CyP21 -> P21 CyP21 -> Cy 0 -> aPcna aPcna -> 0 iPcna -> P21 P21 + aPcna -> iPcna iPcna -> P21 + aPcna iPcna -> aPcna Rc -> pRc pRc -> Rc aPcna + pRc -> aRc aRc -> aPcna + pRc iPcna + pRc -> iRc iRc -> iPcna + pRc P21 + aRc -> iRc iRc -> P21 + aRc iRc -> aRc aRc -> Dna + aRc Rc -> 0 pRc -> 0 aRc -> aPcna iRc -> iPcna MrnaP53 -> MrnaP53 + P53 P53 -> 0 0 -> Dam aRc -> Dam + aRc Dam -> 0