*Appendix D.1. Freezing*

This process can be carried out when the cells are over 90% confluence in p100 dishes. Freezing medium is needed to be prepared at 2–8 ◦C before use. Due to freezing medium contains dimethyl sulfoxide (DMSO), which is known to facilitate the entry of organic compound into human tissues, it is necessary to handle freezing medium carefully with proper personal protective equipment (PPE). A freezing container with isopropanol is needed to be prepared in room temperature. Once the isopropanol chamber is used five times for freezing, the isopropanol in the container must be replaced with fresh isopropanol.

