Figure 4.

Acetylated metastasis-associated protein 1 has oncogenic activity and stimulates Ras pathway. (A) Growth characteristics of Rat1/pcDNA, Rat1/wild-type MTA1 and Rat1/MTA1-K626R clones. (B) The effect of MTA1 mutants on cell migration in Rat1 cells. Five-thousand cells of pcDNA, wild-type MTA1 and MTA1-K626R stable clones in Rat1 cells were loaded onto an insert of Boyden chamber with a pore size of 8 μm. (C) The effect of MTA1 mutants on cell invasiveness in Rat1 cells. (D) The effect of MTA1 mutants on the foci-formation ability of Rat1 cells. Approximately, 2,000 cells per plate of pcDNA, wild-type MTA1 and MTA1-K626R Rat1 stable clones. (E) In vivo tumour formation by wild-type MTA1 clones. Approximately, 5 × 10⁶ cells of Rat1/pcDNA, wild-type MTA1 or MTA1-K626R clones were bilaterally injected into the mammary fat pads of eight athymic nude mice. (F) Tumours derived from the experiment in (E) were embedded into paraffin; sections were made and H&E staining was used to identify the tumours. Histological characteristics of tumours No. 1 and No. 2, malignant histiocytomas with giant cells; No. 3, abundance of blood vessels of the tumour tissue; No. 4, active mitosis (arrows); and No. 5 and No. 6, fusiform fibrosarcoma tumour cells arranged in various orientations. (G) MTA1-AcK626, MTA1 and pERK staining in primary breast cancer samples. Breast cancer tissue microarrays were stained with MTA1-AcK626, pERK and MTA1, and the staining was scored as low and high. (H) Model elucidating the mechanism of MTA1 regulation of the Ras pathway. ERK, extracellular signal-regulated kinase; H&E, haematoxylin and eosin; MTA1, metastasis-associated protein 1; wt, wild type.