PIK3CD and mantle cell lymphoma: Notably, it was also found that dynamic feedback interaction between MCL cells and stromal cells also contributes to ibrutinib resistance development and reciprocal activation of PI3K-AKT-mTOR as well as Integrin-B1 signaling, which could be reversed by combined disruption of BCR signaling with ibrutinib and PI3K-AKT-mTOR axis with GS-1101 (p110δ inhibitor) [15].