Only certain genes are being expressed and it's the family of genes that are being expressed in a cell, likewise the family that are not being expressed, that determines what a cell is like, how it functions.

只有某些特定的基因在细胞中表达,那些在细胞中表达的基因,与那些没有表达的基因,共同决定了细胞的形态和功能

耶鲁公开课 - 生物医学工程探索课程节选