Complex sentence: In 1999, Shu's team studied downstream signaling by TRAIL receptors, they found out a signaling cascade can mediate TRAIL induced NF-κB activation, and TRAIL-induced apoptosis cannot be blocked by it.
Split into simpler sentences: In 1999, Shu's team studied downstream signaling by TRAIL receptors. They discovered that a signaling cascade can mediate TRAIL-induced NF-κB activation, and TRAIL-induced apoptosis cannot be blocked by it.