The relative mRNA level of ZIC1--5 in meningioma groups of different histological grades. The transcript levels were deduced from a recent microarray analysis  that includes eight each of Grade I (benign, open bar), Grade II (atypical, gray bar), and Grade III (anaplastic, malignant, black bar) meningiomas. The transcript levels in meningioma are indicated as relative to the level in normal dura mater. Each bar indicates the mean of eight independent tumor specimens. Error bars indicate the standard error of the mean. The asterisks above bars indicate the statistical significance of the difference between the meningioma classes and the dura maters, and the asterisk above the bracket indicates that of the ZIC1 expression difference between Grade I and Grade II meningiomas. *, P < 0.05; **, P < 0.01; ***, P < 0.001 in Welch's t-test.