UCI Big Dataset,
https://archive.ics.uci.edu/ml/datasets/Mice+Protein+Expression#
has protein expression levels among control and down-syndrome
(trisomic) mice with and without learning excitations.

Eight classes are shown among
control/trisomic, stimulated/not stimulated, and
saline/meantine.

When four classes in control and trisomic mice are combined,
identify subsets of proteins that contribute to distinction between
the two classes (control/trisomic).

If you repeat the question in four classes (contro/trisomic,
stimulated/not stimulated), what are proteins that contribute to
the distinction among classes.

Repeat the same for eight classes.

Is there a relationship as you consider more classes ?