Alexander Jacob Varshavsky (born 8 November 1946) is a Russian-American biochemist, noted for his discovery of the N-end rule of ubiquitination. A native of Moscow,he is currently researching at Caltech.Varshavsky provided an original approach to killing cancer cells, proffering the idea of a targeted molecular device that could enter a cell, examine it for DNA deletions specific to cancer and killing it if it meets the right profile. "(It) involves, in a nutshell, the finding of a genuine Achilles' heel of cancer cells, i.e. their potentially vulnerable feature that won't change during tumor progression," said Varshavsky.

The approach termed deletion-specific targeting (DST), employs HDs (homozygous DNA deletions) as the targets of cancer therapy. "In contrast to other attributes of cancer cells, their HDs are immutable markers. If the DST strategy can be implemented in a clinical setting, it may prove to be both curative and free of side effects."He received the Breakthrough Prize in Life Sciences in 2014 for his discovering critical molecular determinants and biological functions of intracellular protein degradation.