Phenotypic switching is switching between multiple cellular morphologies.
David R. Soll described two such systems: the first high frequency switching system between several morphological stages and a second high frequency switching system between opaque and white cells.
The latter is an epigenetic switching system[1][2] Phenotypic switching in Candida albicans is often used to refer to the epigenetic white-to-opaque switching system.
C. albicans needs this switch for sexual mating.
[4] A second example occurs in melanoma, where malignantly transformed pigment cells switch back-and-forth between phenotypes of proliferation and invasion in response to changing microenvironments, driving metastatic progression.