Loss of heterozygosity (LOH) in a cell is the loss of normal function of one allele of a gene in which the other allele was already inactivated.
locus is the position of a gene or mutation on a chromosome
a microarray is a grid of DNA segments of known sequence that is used to test and map DNA fragments.
the expression profile is a high dimensional vector of gene expression values (RNA abundances) that characterize different types of cells.
A signaling molecule is a chemical involved in transmitting information between cells. Such molecules are released from the cell sending the signal, cross over the gap between cells, and interact with receptors in another cell, triggering a response in that cell.