Principal component representation for the training set. The profiles of the 44 Bone, 20 Muscle, and 5 Adipocyte training set qualifiers present in the C2C12 reduced data set (N _χ²  = 2500) are projected onto the space defined by their first three principal components. (Bone) Red; (Muscle) blue; (Adipocyte) yellow. (ALP) Alkaline phosphatase; (col) collagen; (THBS) thrombospondin; (myosin H and L) myosin heavy and light chains, respectively; (g) gamma-actin; (c) creatine kinase. Numbers in parenthesis indicate multiplicity of qualifiers mapping to the same gene.