Fig 4. Whole blood microRNA expression among cases and controls.

A heat map, with its pseudo-color scale underneath, depicts Z-scaled log₂-transformed microarray signal values for the study's 598 expressed microRNAs among its 161 cases and controls. Unsupervised hierarchical clustering is used to order the samples and microRNAs, dendrograms for which are drawn based on uncentered Pearson correlations, average linkages, and leaf order optimization. Node heights are indicated by the scales next to the dendrograms. Lower-level detail of the sample dendrogram beyond a distance threshold is not shown, with elements on the nodes below the threshold instead depicted as one cluster (black and grey bars). Graphs at the top of the figure indicate cohort membership (case or control) of the samples, and their age (in years), gender, institution (RPCI, Roswell Park Cancer Institute), and blood hemoglobin (g/dl), platelet count (x10³/ul), and white blood cell (WBC) count (x10³/ul) values (if known). Adenocarcinoma (AC) or squamous cell carcionoma (SCC) histology of cancer, presence of a benign nodule in controls, or their being at high risk to develop lung cancer, and sample identities (ID) are also indicated.