4-Hydroxytamoxifen ≥70% Z isomer (remainder primarily E-isomer)

Cell permeable, synthetic estrogen receptor ligand. Widely used in genome engineering. ≥70% Z isomer (remainder primarily E-isomer).

CreER system:

De facto standard compound in drug-inducible manipulation of CreER recombinase. Allows external temporal control of Cre activity in vivo.

May also be used for TRAPing / in the TRAP / TRAP2 system (Targeted recombination in active populations).

CRISPR/Cas9 gene editing:

Activates an inactived Cas9 nuclease (rendered inactive by insertion of a 4-OHT dependent-intein) to reduce off-target CRISPR-mediated gene editing (once bound with 4-OHT, conditionally active Cas9s modify target genomic sites with ~25-fold higher specificity than wild-type Cas9).

Also allows tight, repeated on-off control of the nuclease activity of the ‘iCas’ Cas9 variant which shows high editing efficiency at multiple loci once bound with 4-OHT.

Pure (Z)-4-hydroxytamoxifen also available.