In the next step, we evaluated the ability of PHOTACs 11-13 to degrade HDAC6 using PROTAC A6 as positive control. To this end, we treated MM.1S cells with 1 µM of 11-13 or A6 for 6 hours. The experiments were conducted in the dark and under light irradiation at 390 nm (see Supporting Information for experimental details; the results are summarized in Figure ).