While this study does not rule out the activity of CJ on NOTCH1 wild-type cells or mechanistically on NOTCH1 full length (NFL1) proteins, it confirms that T-ALL is sensitive to Ca2+-ATPase suppression further supporting the need to explore SERCA inhibitors with binding sites different from the one of thapsigargin in search of small molecules with tolerable off-target effects. Here, NOTCH1 is linked to acute lymphoblastic leukemia.