Referee 2's review:

In this study, authors examined the Sprouty2 and BDNF gene expression in dorsolateral prefrontal cortex from the Stanley Array Collection by Quantitative real-time PCR analysis. They found significantly decreased expression of sprouty2 and BDNF in both schizophrenia and bipolar disorder. Furthermore, they showed a significant correlation between these two genes. Long-term treatment with haloperidol or olanzapine showed differential effects on both sprouty2 and BDNF protein levels in the frontal cortex of rats.

Comments:
1) Stanley Array Collection was composed of 35 schizophrenia, 35 bipolar disorder and 35 controls. However, authors used 35 schizophrenia, 31 bipolar disorder and 34 controls. Authors should explain the reason why they did use selected samples.
2) They used GAPDH as a reference. The value of GAPDH should be shown. The reduced expression of the Sprouty2 and BDNF gene, which are normalized by GAPDH, could be due to the results of the increased expression of GAPDH. They should also examine another reference gene such as beta actin.
3) In animal study, they used only 5-6 animals in each group. More than 10 animals in each group are required.
4) Authors measured the Sprouty2 and BDNF protein in rats. To compare the results from human, they should measure mRNA levels of these two genes.
5) Animal data indicated the markedly differential expression of the Sprouty2 and BDNF protein between the typical and atypical antipsychotics. Correlational analysis between antipsychotic medication and these two gene expressions should be performed with the typical or atypical antipsychotics, if possible.
6) There are several writing errors in the text.

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N.B. These are the comments made by the referee when reviewing an earlier version of this paper. Prior to publication the manuscript has been revised in light of these comments and to address other editorial requirements.