Comparison of calbindin D9k, sucrase-isomaltase, and cdx-2 mRNA level among three Caco-2 cell lines. Parental Caco-2 (P) and two well differentiating clones of Caco-2 (BBe and TC7) were harvested at 2 days (50% confluent, proliferating cultures), 4 days (confluence), 8 days (4 days postconfluent, postproliferative), and 15 days (11 days postconfluent, well-differentiated) after seeding. Calbindin D9k, sucrase-isomaltase, and cdx-2 mRNA levels were analyzed by semiquantitative RT-PCR. Each value represents the means ± SE (n = 6) for calbindin D9k (A), sucrase-isomaltase (B), and cdx-2 (C). a, Significantly different from 2-day expression; b, significantly different from parental expression (Fishers least significant difference test, P < 0.05).