The Collaborative International Dictionary of English v.0.48:

cytotaxis \cy`to*tax"is\ (s[imac]`t[-o]*t[a^]k"s[i^]s), n.
   (Biology)
   The movement of cells toward or away from other cells, as a
   result of some stimulation, such as chemical signals
   transmitted and received by the cells.
   [PJC]