The anti-graft watchdog of the Communist Party of China (CPC) has launched an investigation into Sun Zhengcai, former secretary of Chongqing Municipal Committee of the CPC, for "serious discipline violation."

The announcement came 10 days after Sun was relieved of the post of Party chief of Chongqing and replaced by Chen Min'er.

The investigation showcases the determination of the CPC Central Committee to strictly govern the Party and that everyone is equal before Party rules.

Sun is not the first senior Party leader to have been placed under investigation. The Central Commission for Discipline Inspection of the CPC has probed officials from low-level "flies" to high-ranking "tigers" since the current leadership took office in late 2012 and announced a high-profile anti-graft crackdown.

Among the tigers felled in the campaign were Zhou Yongkang, a former member of the Standing Committee of the Political Bureau of the CPC Central Committee; Bo Xilai, former Party chief of Chongqing Municipality; Xu Caihou and Guo Boxiong, both former top generals and vice chairmen of the Central Military Commission; as well as Ling Jihua and Su Rong, former vice chairmen of China's top political advisory body.

The handling of these cases demonstrate that all people are equal before Party regulations, and the enforcement of such rules allows no privilege or exception.

Each and every Party member -- no matter how experienced or how high their position -- must obey the Party's political disciplines and rules. To ensure that, they must exercise caution in their words and deeds, remain politically loyal and consolidate their sense of rules and discipline.

Sun's case showed the line drawn by Party discipline can never be crossed and political regulations and rules should not be taken lightly.

The key to strict governance of the CPC relies on the "key few" leading officials, referring to leading officials at the central, provincial and local levels.

If the key few leading officials are derelict in duty or violate the law and discipline, the result is not just corrupt individuals, but likely that a group of cadres will be led astray and the political ecology of a department or locality will be poisoned.

Leading officials should take a lead in strengthening their political capability and ideals, implementing the Party's decisions and strictly observing Party rules.

Since 2012, the CPC has rolled out a string of measures to strengthen the strict ruling of its more than 89 million members, from the frugality campaign which has curbed extravagance and improved official work style, to a series of regulations aimed at standardizing CPC members' behavior and reducing corruption.

These efforts have helped Party members consolidate their communist beliefs, adhere to the basic Party line and win public trust.

The strict rule of the Party is an ongoing cause. Although remarkable results have been achieved, the situation is still arduous and more must be done to root out the scourge that threatens the Party's very survival.