HDAC1 and osteosarcoma: Mitotic phosphorylation of HDAC1 was detected also in other cell types: 293T fibroblasts, U2OS and Saos-2 osteosarcoma cells, normal and tumoral primary human breast cells, independently from their p53 expression (data not shown) indicating that mitotic phosphorylation of HDAC1 is a general hallmark of mitosis.