Figure 2: Statistical analysis of microarray (SAM) plot of MG63 cultured on PT disks versus control. Expected differentially expressed genes are reported along the axis, whereas observed differentially expressed genes are along the axis. Downregulated genes (green dots) are located in the lower left side of the diagram; upregulated genes (red dots) are in the upper right side; genes with different expression but statistically not significant are depicted in black. Parallel lines drawn from lower-left to upper-right squares are the cut-off limits. The solid line indicates the equal value of observed and expected differentially expressed genes.