In a previous study using microarrays (Roxström-Lindquist et al., 2005), analysis of global changes in gene transcription in differentiated IECs (e.g., Caco-2) co-incubated with the WB isolate showed that, as early as 1.5 h of interaction, Giardia induces the transcription of chemokine ligand genes (ccl20, ccl2, cxcl1-3) whose products are required for attracting immune cells to the site of infection. This evidence concerns the gene CCL2 and infection.