Figure 4.

RT–PCR analysis of laminin chain expression in the thymus. Total RNA isolated from juvenile thymic tissue was reverse-transcribed, amplified with specific primer pairs for human laminin α1, γ2 and γ3 chains, and separated on a 2% agarose gel (lanes 1, 3, and 5). As positive controls, cDNAs from long-term bone marrow culture stromal cells, human umbilical vein endothelial cells and a human skin biopsy were also amplified with the primer pairs for laminin α1, γ2 and γ3 chains, respectively (lanes 2, 4, and 6). The following specific amplification products were detected: a 357-base pair (bp) signal for the α1 chain (lane 2), a 579-bp signal for the γ2 chain (lanes 3 and 4) and a 556-bp signal for the γ3 chain (lanes 5 and 6). Note that no signal for the α1 chain could be detected in the thymic tissue (lane 1), whereas a weak, but still detectable signal for the γ3 chain (lane 5) was obtained with thymic tissue RNA. Lane 7 represents a 100-bp ladder.