How does Cellminer's "Cross-correlations of transcripts, drugs, and microRNAs" work I have seen one of Cellminer tools. I am not sure how do they calculate the cross correlation of the genes, what does it actually mean? Based on what databases? 

For example if I take their example input (HUGO format): 

abcb1
BRCA2
CNBP


I get the following cross correlation matrix (based on what signals).

Identifier      abcb1   BRCA2   CNBP
abcb1           1      -0.142   0.069
BRCA2          -0.142   1       0.176
CNBP           0.069    0.176   1
In the article describing Cellminer says about the cross-correlations:


  ... a cross-correlation table of the resultant z-scores can be
  generated ...


On page 3503

And the z-scores are defined previously as:


  The tool output includes relative transcript intensity presented
  as z-scores...