{'fraction_non_alphanumeric': 0.025, 'fraction_numerical': 0.015384615384615385, 'mean_word_length': 4.371134020618556, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Checkpoints Take the Next Step

Checkpoints are times during the cell cycle when the cell can choose to pause if something is amiss—if its DNA is damaged or if there is a mistake in the synthesis of the new DNA—so that the damage can be repaired. The proteins of these pathways have been defined genetically. Now Carr discusses new biochemical evidence from yeast, presented in two papers in this week's issue of Science (pp. 353 and p. 357), that start to elucidate the functions of two of these proteins—Chk1 and Rad3.