penetration

in cell biology
https://doi.org/10.1351/goldbook.15965
  1. Action of entering or passing through a cell membrane.
  2. Ability or power to enter or pass through a cell membrane.
Source:
PAC, 2007, 79, 1153. (Glossary of terms used in toxicology, 2nd edition (IUPAC Recommendations 2007)) on page 1279 [Terms] [Paper]