Fig. 4.

LUPIN release of ibrutinib. Ibrutinib release by LUPIN was demonstrated by competition with ibrutinib-Cy3 (9) derivative in SKBR3 cells overexpressing ErbB2. SKBR3 cells were treated with either the prodrug alone (7) or prodrug (7) + LUPIN for 30 min; then the cells were treated with ibrutinib-Cy3 (9). The lower fluorescence observed for the LUPIN-uncaged product population indicates that the ErbB2 was saturated with the uncaged prodrug. Conditions for LUPIN release: SNAP-NLuc-DHFR labeled with BG-(Ru)(PNA)-MTX (1) (10 nM), PNA-PyIbr (7) (5 µM), sodium ascorbate (10 mM), furimazine (100 µM), and Ibr-Cy3 (9) (50 nM). Scale bar: 20 µm