- The molecular weight listed may be attributed to either of the histone isoforms listed or to a mixture of these. Two-fold increases and decreases are indicated with ↑↑ or ↓↓, respectively. Increases and decreases that were less than two-fold are indicated with ↑ or ↓, respectively. Increases and decreases where the median expression for one of the groups was 0, thus prohibiting calculation of fold-changes, is indicated by
or
, respectively