MAPK1 and osteosarcoma: A previous study has indicated that p38 mediated activation of Mitogen-activated protein kinase-activated protein kinase 2 (MK2) is necessary for DOX-induced G2/M arrest in U2OS human osteosarcoma cells [43], while others have demonstrated that ERK1/2 activation following topo II poison treatment is associated with G2/M cell cycle arrest [44].