Since the p53pp is final reactant in the p53 signaling network, individual variability in p53 signaling network quantitatively has an impact.Lustig, Hasher and Zacks differentiated among access, deletion and restraint inhibitory functions. In addition to definitional problems, advancements in the field are hampered by measurement problems, such as the use of complex tasks that require multiple processes in addition to inhibition. Also problematic is the widespread use of subtraction or difference scores for estimating inhibitory efficiency, which tend to show much poorer reliability than their constituent scores. Such measurement and analytical problems make it difficult to interpret findings from different inhibitory tasks. Here, we describe a preliminary study on whether two widely-used tests of inhibition–the Stroop and stop-signal tasks–measure the same type of inhibitory ability. Both tasks are often used to index prepotent response inhibition. However, the extent to which they measure the same construct is unclear. A typical Stroop task contains two overlapping stimulus-response dimensions. In the classic color-word Stroop task, participants are asked to name the inkcolor in which a color-word is printed. Interference, also known as the Stroop effect, occurs when the relevant and irrelevant dimensions lead to overlapping but incongruent responses. Compared to a neutral or congruent stimulus, naming of the ink-color takes longer and often results in intrusion errors. Facilitation occurs in the congruent condition where the two dimensions lead to compatible responses, resulting in faster and more accurate responses. Stroop facilitation and interference effects are usually attributed to word-reading being the more practiced and hence more prepotent stimulus-response dimension than color-naming. Accurate performance on incongruent trials is commonly thought to be achieved by selective inhibition dampening the fast automatic activation associated with word-reading, so the slower deliberate route associated with color-naming may be completed. Stroop interference, measured by the difference in latency or accuracy between the incongruent and neutral or incongruent and congruent conditions, is typically taken to reflect inhibitory ability or efficiency. It should be noted that we limit our scope here to stop-signal tasks based on Logan and Cowan’s paradigm. Such choicereaction-time tasks typically involve centrally presented stimuli and manual key-press responses, and are commonly used in cognitive psychology to study individual, clinical and developmental differences in the inhibition of responses. Other countermanding paradigms have been used to study the inhibition of saccadic eye or arm reaching movements to peripheral stimuli in both monkeys and humans. Both the Stroop and stop-signal tasks can be seen as requiring the inhibition of a prepotent or NSC 136476 well-practiced response.