Proliferating Cell Nuclear AntigenCell ProliferationCells, CulturedSignal TransductionCell DivisionApoptosisCell DifferentiationCell Line, TumorCell CycleLymphocyte ActivationBromodeoxyuridineCell MovementCell SurvivalRNA, MessengerImmunohistochemistryMice, Inbred C57BLCell LineKi-67 AntigenBlotting, WesternPhosphorylationT-LymphocytesReverse Transcriptase Polymerase Chain ReactionStem CellsFlow CytometryTumor Cells, CulturedMice, Knockout